Compilare: user.cpp: In function ‘int main()’: user.cpp:61:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < Pairs.size(); ++i) { ^ user.cpp:40:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("piese3.in", "r", stdin); ^ user.cpp:41:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("piese3.out", "w", stdout); ^