/in/foo.cc: In function 'void bfs()':
/in/foo.cc:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<a[x].size();i++)
               ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:52:12: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(y%2==0&&b[x]<=y||y%2==1&&c[x]<=y)
      ~~~~~~^~~~~~~~~