Compilare: main.cpp: In function 'void dfs(long long int, long long int)': main.cpp:35:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(long long i=0;i<vecini[x].size();++i) if(!seen[node]) dfs(r,node); ~^~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:102:55: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=l;++i,cout<<'\n') for(int j=0;j<comp[i].size();++j) cout<<comp[i][j]<<' '; ~^~~~~~~~~~~~~~~ main.cpp:85:32: 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); ^ main.cpp:86:34: 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); ^