#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define maxn 40

typedef long long ll;

bool ok;
int n;

void solve(int dep, const string& str){
    if(ok)
        return;
        
    if(dep == 0){
        for(int i = 0; i < n; i++){
            if(str[i] == '0')
                return;
        }
        ok = 1;
        return;
    }
    
    for(int i = 0; i < n; i++){
        string nstr = str;
        for(int j = 0; j < n; j++){
            if(i + j < n && str[j] == '1')
                nstr[j + i] = '1';
        }
        solve(dep - 1, nstr);
    }
}


int main(){
    ok = 0;
    string str;
    cin >> str;
    n = str.length();
    int ans = -1;
    if (str[0] != '0') {
    for(int dep = 0; dep <= 6; dep++){
        solve(dep, str);
        if(ok){
            ans = dep;
            break;
        }
    }
    }
    printf("%d\n", ans);
    return 0;
}