Compilare: user.cpp: In function ‘void prim()’: user.cpp:22:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<vec[1].size();i++) ^ user.cpp:38:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<vec[n1].size();i++) ^ user.cpp:40:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<vec[n2].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:60:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<ans.size();i++) cout << ans[i].first << " " << ans[i].second << endl; ^ user.cpp:47:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in","r",stdin); ^ user.cpp:48:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out","w",stdout); ^