function to check if point collinear or not
static void cool_line ( int x1 , int y1 , int x2 , int y2 , int x3 , int y3 ) { if ( ( y3 - y2 ) * ( x2 - x1 ) == ( y2 - y1 ) * ( x3 - x2 ) ) Console . WriteLine ( " Yes " ) ; else Console . WriteLine ( " No " ) ; }