#include<bits/stdc++.h>
using namespace std;
int main(){ 
    int a,b,c,d,x,z,s;
    cin>>x;
    a=x%10;
    b=x/10%10;
    c=x/100%10;
    d=x/1000%10;
    z=a*1000+b*100+c*10+d;
    s=x-z;
    cout<<s;  
}
/**************************************************************
	Problem: 1702
	User: xuezihong1
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/