C :

#include <stdio.h>
#include <stdlib.h>
#define swap(a,b) t=a;a=b;b=t;
int main(int argc, char *argv[])
{
  int a,b,t;
  scanf("%d%d",&a,&b);
  swap(a,b);
  printf("%d %d",a,b);

  return 0;
}

C++ :

#include<iostream>
using namespace std;
int main()
{
int a,b;
cin>>a>>b;
cout<<b<<" "<<a<<endl;
}

Pascal :

var a,b:integer;
begin
  readln(a,b);
  write(b,' ',a);
end.