/in/foo.cc: In function 'int main()':
/in/foo.cc:16:6: error: 'i' was not declared in this scope
  for(i = 0; i < n; i++)
      ^
/in/foo.cc:21:6: error: 'i' was not declared in this scope
  for(i = 0; i < n; i++)
      ^
/in/foo.cc:28:6: error: 'i' was not declared in this scope
  for(i = n-1; i >= 0; i--)
      ^