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

}
/**************************************************************
	Problem: 1702
	User: yangjunwen
	Language: C++
	Result: Accepted
	Time:40 ms
	Memory:2072 kb
****************************************************************/