/in/foo.cc: In function 'int main()':
/in/foo.cc:47:15: warning: 'na' is used uninitialized in this function [-Wuninitialized]
  Output(a, na);
               ^
/in/foo.cc:48:15: warning: 'nb' is used uninitialized in this function [-Wuninitialized]
  Output(a, nb);
               ^