#include<bits/stdc++.h>
using namespace std;
int main(){
	int a,b,c,d,e,n;
	cin>>n;
	a=n%10;
	b=n/10%10;
	c=n/100%10;
	d=n/1000;
	e=c*1000+d*100+a*10+b;
	cout<<e;
}
/**************************************************************
	Problem: 1619
	User: zengyixuan
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/