added cities

vec.py

@@ -33,3 +33,6 @@ class Vec2:
 
     def cross(self, v: "Vec2") -> float:
         return self.x * v.y - self.y * v.x
+
+    def scale(self, v: "Vec2") -> "Vec2":
+        return Vec2(self.x * v.x, self.y * v.y)