#include <bits/stdc++.h>

#define FOR(n, a, b) for(size_t n = (a); n < (b); ++n)
#define ALL(x) x.begin(), x.end()
#define pb push_back
#define st first
#define nd second

using namespace std;

typedef long long ll;
typedef pair<int, int> pint;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pint> vii;

unsigned long long n;
string s;

string move_str(string s, int k) {
    string s1 = s;
    FOR(i, 0, s.size()-k) {
        s1[i+k] = (s[i] == '1' || s[i+k] == '1') ? '1' : '0';
    }
    return s1;
}


int first_zero(string s) {
    FOR(i, 1, s.size()) {
        if(s[i] == '0') return i;
    }
    return -1;
}


int check(string s) {
    if(first_zero(s) == -1) return 0;
    return check(move_str(s, first_zero(s))) + 1;
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    cin >> s;

    cout << check(s) << '\n';

    return 0;
}