C :

#include<stdio.h>
int main(void)
{
	float a,b,c;
	scanf("%f%f", &a,&b);
	printf("%g %g\n",a,b);
	c=a;
	a=b;
	b=c;
	printf("%g %g",a,b);	
	return 0;
}

C++ :

#include <iostream>

using namespace std;

int main()
{
    double x,y,temp;
    cin>>x>>y;
    cout<<x<<" "<<y<<endl;
    temp=y;
    y=x;
    x=temp;
    cout<<x<<" "<<y<<endl;
    return 0;
}