/in/foo.cc: In function 'bool check(double, Point*, int, Point*, int)':
/in/foo.cc:305:13: warning: unused variable 'p' [-Wunused-variable]
         int p = 0;
             ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:343:11: warning: operation on 'n' may be undefined [-Wsequence-point]
     pol[n ++] = Point(pol[n-1].x, 0);
         ~~^~