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

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