diff --git a/src/main.rs b/src/main.rs
index 5d25ad7..48547fc 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -12,6 +12,7 @@ pub struct Trail {
     distance: i32,
     area: i32,
     size: i32,
+    pocket: i32,
 }
 
 impl Trail {
@@ -24,12 +25,13 @@ impl Trail {
             distance: 0,
             area: 0,
             size: 0,
+            pocket: 0,
         }
     }
 
     pub fn start(&mut self, way: String) -> DistArea {
         if !way.is_empty() {
-            let mut da = DistArea{dist: 0, area: 0, size: 0};
+            let mut da = DistArea{dist: 0, area: 0, size: 0, pocket: 0};
             let split = way.split_whitespace();
             let mut plan : Vec<String> = Vec::new();
             for s in split {
@@ -46,12 +48,14 @@ impl Trail {
             self.calc_max();
             self.calc_area();
             self.calc_size();
+            self.calc_pocket();
             da.dist = self.distance;
             da.area = self.area;
             da.size = self.size;
+            da.pocket = self.pocket;
             da
         } else {
-            DistArea{dist:0, area:0, size:0}
+            DistArea{dist:0, area:0, size:0, pocket: 0}
         }
     }
 
@@ -171,68 +175,123 @@ impl Trail {
     fn calc_pocket(&mut self) {
         for i in self.min.x .. self.max.x {
             for j in self.min.y .. self.max.y {
+                if DEBUG {
+                    println!("pocket: p: ({},{})", i, j);
+                }
                 if self.is_in_pocket(Point{x: i, y: j}) {
-                    self.size += 1;
+                    self.pocket += 1;
                     if DEBUG {
-                        println!("p: ({},{})", i, j);
+                        println!("({},{}) is in pocket", i, j);
                     }
                 }
             }
         }
     }
+
     fn is_in_pocket(&self, point: Point) -> bool {
         let mut left = 0;
         let mut right = 0;
         let mut top = 0;
-        let mut down = 0;
+        let mut bottom = 0;
         let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_,p)| p.y == point.y && p.x <= point.x);
         for (i, p) in f {
             if self.directions[i] == Direction::South {
                 left += 1;
                 if DEBUG {
-                    print!("{:?} {:?} ", p, self.directions[i]);
+                    print!("{:?} {:?}; ", p, self.directions[i]);
                 }
             }
         }
-        f = self.waypoints.clone().into_iter().enumerate().filter(|&(_,p)| p.y == point.y+1 && p.x <= point.x);
+        let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_,p)| p.y == point.y+1 && p.x <= point.x);
         for (i, p) in f {
             if self.directions[i] == Direction::North {
                 left += 1;
                 if DEBUG {
-                    print!("{:?} {:?} ", p, self.directions[i]);
+                    print!("{:?} {:?}; ", p, self.directions[i]);
                 }
             }
         }
         if DEBUG {
-            println!("- {} ", left);
+            println!("left {} ", left);
         }
 
-        if left % 2 != 0 || left == 0 {
-            return false;
+        if left % 2 == 0 && left > 0 {
+            let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_, p)| p.y == point.y && p.x > point.x);
+            for (i, p) in f {
+                if self.directions[i] == Direction::South {
+                    right += 1;
+                    if DEBUG {
+                        print!("{:?} {:?}; ", p, self.directions[i]);
+                    }
+                }
+            }
+            let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_, p)| p.y == point.y + 1 && p.x > point.x);
+            for (i, p) in f {
+                if self.directions[i] == Direction::North {
+                    right += 1;
+                    if DEBUG {
+                        print!("{:?} {:?}; ", p, self.directions[i]);
+                    }
+                }
+            }
+            if DEBUG {
+                println!("right {} ", right);
+            }
+
+            if right % 2 == 0 && right > 0 {
+                return true;
+            }
         }
 
-        f = self.waypoints.clone().into_iter().enumerate().filter(|&(_,p)| p.y == point.y && p.x > point.x);
+        let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_,p)| p.x == point.x && p.y <= point.y);
         for (i, p) in f {
-            if self.directions[i] == Direction::South {
-                right += 1;
+            if self.directions[i] == Direction::West {
+                bottom += 1;
                 if DEBUG {
-                    print!("{:?} {:?} ", p, self.directions[i]);
+                    print!("{:?} {:?}; ", p, self.directions[i]);
                 }
             }
         }
-        f = self.waypoints.clone().into_iter().enumerate().filter(|&(_,p)| p.y == point.y+1 && p.x > point.x);
+        let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_,p)| p.x == point.x+1 && p.y <= point.y);
         for (i, p) in f {
-            if self.directions[i] == Direction::North {
-                right += 1;
+            if self.directions[i] == Direction::East {
+                bottom += 1;
                 if DEBUG {
-                    print!("{:?} {:?} ", p, self.directions[i]);
+                    print!("{:?} {:?}; ", p, self.directions[i]);
                 }
             }
         }
         if DEBUG {
-            println!("- {} ", left);
+            println!("bottom {} ", bottom);
+        }
+
+        if bottom % 2 == 0 && bottom > 0 {
+            let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_, p)| p.x == point.x && p.y > point.y);
+            for (i, p) in f {
+                if self.directions[i] == Direction::West {
+                    top += 1;
+                    if DEBUG {
+                        print!("{:?} {:?}; ", p, self.directions[i]);
+                    }
+                }
+            }
+            let mut f = self.waypoints.clone().into_iter().enumerate().filter(|&(_, p)| p.x == point.x + 1 && p.y > point.y);
+            for (i, p) in f {
+                if self.directions[i] == Direction::East {
+                    top += 1;
+                    if DEBUG {
+                        print!("{:?} {:?}; ", p, self.directions[i]);
+                    }
+                }
+            }
+            if DEBUG {
+                println!("top {} ", top);
+            }
+            if top % 2 == 0 && top > 0 {
+                return true;
+            }
         }
-        right % 2 == 0 && right > 0
+        false
     }
 }
 
@@ -326,6 +385,7 @@ pub struct DistArea {
     pub dist: i32,
     pub area: i32,
     pub size: i32,
+    pub pocket: i32,
 }
 
 impl PartialEq for DistArea {
@@ -333,6 +393,7 @@ impl PartialEq for DistArea {
         let mut res = self.dist == other.dist;
         res &= self.area == other.area;
         res &= self.size == other.size;
+        res &= self.pocket == other.pocket;
         res
     }
 }
@@ -477,4 +538,49 @@ mod tests {
 
         assert_eq!(res.size, 1156);
     }
+
+    #[test]
+    fn level4_1() {
+        let input = String::from("1 FFFR 4");
+        let mut trail = Trail::new();
+        let mut res = trail.start(input);
+
+        assert_eq!(res.pocket, 0);
+    }
+
+    #[test]
+    fn level4_2() {
+        let input = String::from("9 F 6 R 1 F 4 RFF 2 LFF 1 LFFFR 1 F 2 R 1 F 5");
+        let mut trail = Trail::new();
+        let mut res = trail.start(input);
+
+        assert_eq!(res.pocket, 4);
+    }
+
+    #[test]
+    fn level4_3() {
+        let input = String::from("14 L 1 FR 1 FFFFFL 1 FFFFL 1 F 12 L 1 F 12 L 1 F 12 L 1 FFFFL 1 FFFFFFFFR 1 FFFR 1 FFFL 1");
+        let mut trail = Trail::new();
+        let mut res = trail.start(input);
+
+        assert_eq!(res.pocket, 29);
+    }
+
+    #[test]
+    fn level4_4() {
+        let input = String::from("32 FFRFLFLFFRFRFLFF 3 R 1 FFLFRFRFLFFF 3 R 1 FFFFFF 3 L 1 FFFRFLFLFRFF 2 R 1 FFFRFLFLFRFF 3 R 1 FFFFFF 1 L 1 FFRFLFLFFRFRFLFF 3 R 1 FFLFRFRFFLFLFRFF 2 L 1 FFLFRFRFFLFLFRFF 3 R 1 FFRFLFLFFRFRFLFF 2 R 1 FFRFLFLFFRFRFLFF 2 L 1 FFFFFF 3 R 1 FFFRFLFLFRFF 5 R 1 FFLFRFRFLFFF 1 L 1 FFLFRFRFFLFLFRFF 2 R 1 FFRFLFLFFRFRFLFF 2 L 1");
+        let mut trail = Trail::new();
+        let mut res = trail.start(input);
+
+        assert_eq!(res.pocket, 111);
+    }
+
+    #[test]
+    fn level4_5() {
+        let input = String::from("10 FFLFRFRFFLFLFRFF 5 L 1 FFFRFLFLFRFF 4 L 1 FFLFRFRFFLFLFRFF 8 L 1 FFLFRFRFFLFLFRFF 4 L 1 FFFFFF 3 R 1");
+        let mut trail = Trail::new();
+        let mut res = trail.start(input);
+
+        assert_eq!(res.pocket, 102);
+    }
 }