#include <stdio.h>

int times2(int x)
{
  return x * 2;
}

int times3(int x)
{
  return x * 3;
}

typedef int (*operation_function)(int);

int doit(int num, operation_function func)
{
  return func(num);
}

int main(int argc, char** argv)
{
  fprintf(stdout, "double %d\n", doit(5, times2));
  fprintf(stdout, "triple %d\n", doit(5, times3));

  return 0;
}