Compilare: user.cpp: In function ‘int main()’: user.cpp:40:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < G[i].size(); ++j){ ^ user.cpp:43:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < G[i].size(); ++j){ ^ user.cpp:46:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < G[nnode].size(); ++k){ ^ user.cpp:63:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ans.size(); ++i){ ^ user.cpp:28:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fof.in","r",stdin); ^ user.cpp:29:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fof.out","w",stdout); ^ user.cpp:30:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:32:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^