/in/foo.cc: In function 'int main()':
/in/foo.cc:8:13: error: 'i' was not declared in this scope
  for(int i0;i<n;i++)
             ^
/in/foo.cc:8:10: warning: unused variable 'i0' [-Wunused-variable]
  for(int i0;i<n;i++)
          ^~