/in/foo.cc:49:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:89:6: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
   if ((dis[x] - dis[fa[fx][0]]) * 2 == tmp)
      ^