#pragma GCC optimize(2)
#pragma GCC optimize(3)
#include <bits/stdc++.h>
using namespace std;

void debug_out() {cerr << endl;}
template <typename Head, typename... Tail> void debug_out(Head H, Tail... T)
{
    cerr << " " << H;
    debug_out(T...);
}
#ifndef ONLINE_JUDGE
    #define debug(...) cerr << "{" << #__VA_ARGS__ << "}:", debug_out(__VA_ARGS__)
#else
    #define debug(...) 42
#endif

int main(){
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    string s;
    cin >> s;
    int n = s.size();
    int target = 0;
    for (int i = 0; i < n; i += 1) {
        target = target * 2 + (s[i] == '0');
    }
    vector<int> dp(1 << n);
    dp[0] = 1;
    int res = 1e9;
    int o = 0;
    for (; !dp[target]; o += 1) {
        auto new_dp = dp;
        for (int mask = 0; mask < (1 << n); mask += 1) {
            if(dp[mask] == 0) continue;
            int new_mask = mask;
            
            for (int i = 0; i <= o; i += 1) {
                new_mask ^= 1 << i;    
            }
            for (int i = 0; i < n; i += 1) {
                new_dp[new_mask] = max(new_dp[new_mask], dp[mask]);
                new_mask ^= 1 << i;
                if(i + o + 1 < n) new_mask ^= 1 << i + o + 1;
            }
        }
        swap(dp, new_dp);
    }
    cout << o << "\n";
    return 0;
}