Compilare: user.cpp: In lambda function: user.cpp:220:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (to_remove.size() - 1 >= i) { ^ user.cpp: In function ‘int main()’: user.cpp:264:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < P.size(); i++) P[i].id = i + 1, M[P[i]] = i + 1, rez[i + 1] = P[i]; ^ user.cpp:238:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rectangles.in","r",stdin); ^ user.cpp:239:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rectangles.out","w",stdout); ^ user.cpp:241:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:243:66: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &R[i].x1, &R[i].y1, &R[i].x2, &R[i].y2); ^