Compilare: user.cpp: In function ‘int main()’: user.cpp:50:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v1[c].size(); i++) ^ user.cpp:52:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < v2[c].size()) ^ user.cpp:54:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j + 1 < v2[c].size() && v2[c][j + 1].first <= v1[c][i].first) j++; ^ user.cpp:65:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j + 1 < v2[c].size() && ans[c].d > abs(v1[c][i].first - v2[c][j + 1].first)) ^ user.cpp:20:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("stalpi3.in", "r", stdin); ^ user.cpp:21:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("stalpi3.out", "w", stdout); ^ user.cpp:25:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &d); ^ user.cpp:30:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &pos, &col); ^ user.cpp:37:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &pos, &col); ^