#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,g,s,b,q,x;
    cin>>n;
	g=n/1%10; 
	s=n/10%10; 
	b=n/100%10; 
	q=n/1000%10;
	x=g*1000+s*100+b*10+q*1;
	cout<<n-x;
    return 0;
}

/**************************************************************
	Problem: 1702
	User: zhangailin
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/