#include <stdio.h>

struct s
{
  int t[2];
};

static void permuter(struct s a)
{
  int aux;

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

int main()
{
  struct s x;

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

  permuter(x);

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

  return 0;
}