/in/foo.cc: In function 'int main()':
/in/foo.cc:37:40: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'll* {aka long long int*}' [-Wformat=]
  for(int i=1;i<=n;i++) scanf("%d",&a[i]);
                                        ^
/in/foo.cc: In function 'int bfs(int)':
/in/foo.cc:33:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^