Compilare: user.cpp: In function ‘void dfs1(int)’: user.cpp:21:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[u].size(); ++i){ ~^~~~~~~~~~~~ user.cpp: In function ‘void dfs2(int)’: user.cpp:31:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<GT[u].size(); ++i){ ~^~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:66:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<sol[i].size();++j) ~^~~~~~~~~~~~~~ user.cpp:41:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in","r",stdin); ^ user.cpp:42:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out","w",stdout); ^ user.cpp:45:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:47:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&u,&v); ^