returns square of distance b / w two points
int lengthSquare ( pair < int , int > X , pair < int , int > Y ) { int xDiff = X . first - Y . first ; int yDiff = X . second - Y . second ; return xDiff * xDiff + yDiff * yDiff ; } void printAngle ( pair < int , int > A , pair < int , int > B , pair < int , int > C ) {