#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,x,q,b,s,g,c=0;
	scanf("%d",&n);
	g=n%10;
	s=n/10%10;
	b=n/100%10;
	q=n/1000;
	x=g*1000+s*100+b*10+q;
	c=n-x;
	printf("%d",c);
} 
/**************************************************************
	Problem: 1702
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/