Compilare: user.cpp: In function ‘int main()’: user.cpp:42:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(y = 0;y < G[x].size();++y) ^ user.cpp:48:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(x = 0;x < G[0].size();++x) ^ user.cpp:19:35: 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:20:37: 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:22:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ",&N,&M); ^ user.cpp:32:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d ",&x,&y,&z); ^