#include <bits/stdc++.h> 
using namespace std;
int main(){
    int a,b,c,d,e;
    cin>>e;
    a=e%10;
    b=e%100/10;
    c=e%1000/100;
    d=e/1000;
    cout<<c<<d<<a<<b;
}
/**************************************************************
	Problem: 1619
	User: xuezihong1
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/