Compilare: user.cpp: In function ‘int calc(int, int)’: user.cpp:15:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < G[last].size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:41:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i < G[0].size();++i) ^ user.cpp:24:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.in","r",stdin); ^ user.cpp:25:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.out","w",stdout); ^ user.cpp:26:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ",&N,&M); ^ user.cpp:32:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d ",&x,&y,&z); ^