Compilare: user.cpp: In function ‘void dfs1(int)’: user.cpp:19:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<a[x].size();i++) ^ user.cpp: In function ‘void dfs2(int)’: user.cpp:32:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<b[x].size();i++) ^ user.cpp: In function ‘void solve()’: user.cpp:56:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<sol[i].size();j++) ^ user.cpp: In function ‘void read()’: user.cpp:67:27: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&n,&m); ^ user.cpp:71:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&x,&y); ^