/in/foo.cc: In function 'int main()':
/in/foo.cc:16:3: warning: statement has no effect [-Wunused-value]
  b%k;
  ~^~
/in/foo.cc:17:29: error: 'tmpd' was not declared in this scope
  printf("%d^%d mod %d=%d\n",tmpd,p,k,f(p));
                             ^~~~
/in/foo.cc:15:6: warning: unused variable 'tmpb' [-Wunused-variable]
  int tmpb=b;
      ^~~~