Compilare: user.cpp: In function ‘void DFS()’: user.cpp:26:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(idx[x] == a[x].size()) --vf; ^ user.cpp:27:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; idx[x] < a[x].size(); ++idx[x]) ^ user.cpp: In function ‘int main()’: user.cpp:46:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d %d",&N,&M); ^ user.cpp:49:34: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d %d",&x,&y); ^