Compilare: user.cpp: In function ‘void DFS(int)’: user.cpp:31:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < q[t].size(); ++i) ^ user.cpp:40:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(idx[t] < a[t].size() ) { stiva[++nr] = a[t][ idx[t]++ ]; ok = 1; } ^ user.cpp: In function ‘int main()’: user.cpp:46:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("stramosi.in","r",stdin); ^ user.cpp:47:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("stramosi.out","w",stdout); ^ user.cpp:51:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&N,&M); ^ user.cpp:54:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ user.cpp:61:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^