/in/foo.cc: In function 'bool dfs(int)':
/in/foo.cc:16:36: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
     for (int i = h[u], v; v = tto[i]; i = nxt[i]) {
                                    ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:42:35: error: 'memset' was not declared in this scope
         memset(vis, 0, sizeof(vis));
                                   ^