Compilare: main.cpp: In function 'int pairup(int)': main.cpp:15:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[nod].size();i++){ ~^~~~~~~~~~~~~~ main.cpp:26:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[nod].size();i++){ ~^~~~~~~~~~~~~~ main.cpp: In function 'void df(int)': main.cpp:40:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[i].size();j++){ ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:57:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("felinare.in","r",stdin); ^ main.cpp:58:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("felinare.out","w",stdout); ^ main.cpp:59:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ main.cpp:61:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^