#include<bits/stdc++.h>
using namespace std;
int main(){
    int jz,j1,j2,j3,j4,z1; 
    cin>>jz;
    j1=jz%10;
    j2=jz/10%10;
    j3=jz/100%10;
    j4=jz/1000;
    z1=j4*1+j3*10+j2*100+j1*1000;
    cout<<jz-z1;
}
/**************************************************************
	Problem: 1702
	User: huanglingkai
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/