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

/**************************************************************
	Problem: 1702
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/