#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    string s;
    cin >> s;
    int ans = 0;
    for (const char c : s) {
        if (c == '0') { ans++; }
    }
    cout << abs(ans - 8) << endl;
    return 0;
}