#28015: _CPP
11030067@mail.hpsh.tp.edu.tw
(和平110級鄧雨珊)
#include <iostream>
#include <cmath>
using namespace std;
int main(){
string x;
while (cin >> x){
int ans=0, sign=1;
for (int i=0; i<x.size(); i++){
ans+=(x[i]-'0')*sign;
sign*=-1;
}
cout << abs(ans) <<endl;
}
}