Compilare: user.cpp: In function ‘int main()’: user.cpp:36:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<elem.size();i++) ~^~~~~~~~~~~~ user.cpp:42:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<nod[pos].size();i++) ~^~~~~~~~~~~~~~~~ user.cpp:55:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<r.size();i++) ~^~~~~~~~~ user.cpp:9:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.in","r",stdin); ^ user.cpp:10:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.out","w",stdout); ^ user.cpp:11:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d",&n,&m,&x,&y); ^ user.cpp:14:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&p1,&p2); ^