/in/foo.cc: In function 'int main()':
/in/foo.cc:6:17: error: 'n' was not declared in this scope
  for(int i=1;i<=n;i++)
                 ^
/in/foo.cc:8:12: error: 'n' was not declared in this scope
  for(int i=n;i>=1;i--)
            ^