#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: chenjiahui
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/