Compilare: main.cpp: In function 'int main()': main.cpp:85:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (dr < P2[i-1].size() && P2[i-1][dr].y <= it.y){ ~~~^~~~~~~~~~~~~~~~ main.cpp:48:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bazar.in","r",stdin); ^ main.cpp:49:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bazar.out","w",stdout); ^ main.cpp:50:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ main.cpp:53:40: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &P[i].x, &P[i].y); ^