#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,g,b,s,q,a=0,h=0;
	cin>>n;
	g=n%10;
	b=n/10%10;
	s=n/100%10;
	q=n/1000;
	a=g*1000+b*100+s*10+q;
	h=n-a;
	cout<<h;
	return 0;
}
/**************************************************************
	Problem: 1702
	User: lijinkai
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/