#include <iostream>
#include <fstream>
#include <string> 
#include <cmath>  
#include <cstdlib>
#include <ctime>
#include <vector>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <functional>
#include <cctype>
#include <list>
//#include <boost/multiprecision/cpp_int.hpp>

#define BIT(a) (1 << (a))

using namespace std;
//using namespace boost::multiprecision;

long long MOD = 1000000007;


long long mod_pow(long long x, long long n){
    long long res = 1;
    for(int i = 0;i < 60; i++){
        if(n >> i & 1) res = res * x % MOD;
        x = x * x % MOD;
    }
    return res;
}



int main(void){
    string N;
    cin >> N;
    int cnt = 0;
    int len = N.length();
    for (int i = 1; i < len; i++){
        if (N[i] == '0') cnt++;
    }
    cout << abs(cnt - 8) << endl;

    return 0;
}