#include <stdio.h>

static void permuter(int a[2])
{
  int aux;

  aux = a[0];
  a[0] = a[1];
  a[1] = aux;
}

int main()
{
  int x[2];

  x[0] = 10;
  x[1] = 20;

  permuter(x);

  printf("%d %d\n", x[0], x[1]);

  return 0;
}