#include <bits/stdc++.h>
using namespace std;
int main(){
	int n,g,s,b,q,h;
	cin>>n;
	g=n%10;
	s=n/10%10;
	b=n/100%10;
	q=n/1000;
	h=g*1000+s*100+b*10+q;
	cout<<n-h;
	
}


/**************************************************************
	Problem: 1702
	User: 15159808820
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/