#include <bits/stdc++.h>
#define rep(i,n)for(long long i=0;i<(n);i++)
using namespace std;
typedef long long ll;
const int MOD=1e9+7;
const int MAX = 1000000;
const int INF = 1e9;
const double pi=acos(-1);

int main(){
  string s;
  cin >> s;
  int ans=0;
  rep(i,s.size()){
    if(s[i]=='0')ans++;
  }
  cout << abs(ans-8)<<endl;
  return 0;
}