#include<bits/stdc++.h>
using namespace std;
int main(){
	int j,x,a,b,c,d;
	scanf("%d",&j);
	a=j%10;
	b=j/10%10;
	c=j/100%10;
	d=j/1000;
	x=c*1000+d*100+a*10+b;
	printf("%d",x); 
	
} 

/**************************************************************
	Problem: 1619
	User: zhengzihao3
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/