#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
#define rep(i, a, n) for (int i = (a); i < (n); i++)
#define per(i, a, n) for (int i = (n) - 1; i >= (a); i--)

ll nx(ll x) {
    ll c = x&-x, r = x+c;
    return (((r^x) >> 2)/c) | r;
}

ll apply(ll a, ll x, int n) {
    ll cur = a;
    for (int i = 0; i <= n; i++) {
        cur |= !!((1ll << (i)) & x) * (cur >> (i+1));
    }
    return cur;
}

void pr(ll x) {
    bitset<64> a(x);
    cout << a << endl;
}

int main(void)
{
	ios_base::sync_with_stdio(false);
    string s;
    cin >> s;
    int n = s.size();
    ll a = 0;
    rep(i,0,n) {
        if (s[i] == '1')
            a |= (1ll << (n-1-i));
    }

//    cout << a << endl;

    ll foo = 0;
    rep(i,0,7) {
        foo |= ((1ll << (1<<i)) - 1);
    }
/*
    cout << foo << endl;
    cout << apply(a, foo, n) << endl;
    cout << ((1ll << 40) - 1) << endl;
    pr(foo);
    pr(apply(a, foo, n));
    pr(((1ll << 40) - 1));
*/
    rep(cnt,1,7) {
        ll tot = 0;
        for (ll x = (1ll << cnt) - 1; x < (1ll << n); x = nx(x)) {
            tot++;
            ll cur = apply(a, x, n);
            if (cur == ((1ll << n) - 1)) {
                cout << cnt << endl;
                return 0;
            }
            //cout << " " << x << endl;
        }
        //cout << tot << endl;
    }
    assert(false);
}