/in/foo.cc: In function 'int digit(int, int)':
/in/foo.cc:8:9: warning: 'r' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return r;
         ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:13:23: warning: 'r' may be used uninitialized in this function [-Wmaybe-uninitialized]
  std::cout<<digit(n,k);
                       ^