/in/foo.cc: In function 'int main()':
/in/foo.cc:81:6: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
    if(vis[u])
      ^
/in/foo.cc:93:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
   if(vis[col[i]])
     ^