Compilare: user.cpp: In function ‘bool cmp2(const std::pair<int, int>&, const std::pair<int, int>&)’: user.cpp:62:14: warning: statement has no effect [-Wunused-value] a.second > b.second; ^ user.cpp:63:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:132:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dsip.in","r",stdin); ^ user.cpp:133:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dsip.out","w",stdout); ^ user.cpp:135:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:136:70: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i = 1; i <= n; i++) scanf("%d%d", &P[i].first, &P[i].second); ^ user.cpp:140:72: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &dA.first, &dA.second, &dB.first, &dB.second); ^