foo.cc: In function ‘void bfs(int)’:
foo.cc:12:9: error: ‘q’ was not declared in this scope
   12 |         q.push(u);vis[u]=i;cout<<u<<' ';
      |         ^
foo.cc:12:26: error: ‘i’ was not declared in this scope
   12 |         q.push(u);vis[u]=i;cout<<u<<' ';
      |                          ^