#include <iostream>     // Input/output stream objects
#include <fstream>      // File stream objects
#include <sstream>      // String stream objects
#include <iomanip>      // Input/output manipulators
#include <string>       // String class and functions
#include <vector>       // Dynamic array
#include <list>         // Doubly linked list
#include <set>          // Set container
#include <map>          // Map container
#include <queue>        // Queue container
#include <stack>        // Stack container
#include <algorithm>    // Algorithms on sequences (e.g., sort, find)
#include <cmath>        // Mathematical functions
#include <climits>      // LLONG_MAX, LLONG_MIN
#include <ctime>        // Date and time functions
#include <cstdlib>      // General purpose functions (e.g., memory management)
#include <cstring>      // C-style string functions
#include <cctype>       // Character classification functions
#include <cassert>      // Assert function for debugging
#include <exception>    // Standard exceptions
#include <functional>   // Function objects
#include <iterator>     // Iterator classes
#include <limits>       // Numeric limits
#include <locale>       // Localization and internationalization
#include <numeric>      // Numeric operations (e.g., accumulate)
#include <random>       // Random number generators
#include <stdexcept>    // Standard exception classes
#include <typeinfo>     // Runtime type information
#include <utility>      // Utility components (e.g., std::pair)
#include <bitset>

using namespace std;

#define FOR(i, a, b) for(int i = a; i < (b); i++)
#define FORE(i, a, b) for(int i = a; i <= (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
#define x first 
#define y second
#define mp make_pair
#define PI 3.141592653
#define compress(coord) sort(all(coord)), coord.resize(unique(all(coord)) - coord.begin())
const double eps = 1e-9;
const ll inf = LLONG_MAX;

string s;
int n;
vector<int> computed;
int solve(int m, int st) {
    if (m == 0) {
        if (st == (1 << n) - 1) return 1;
        else return 0;
    }
    if (solve(m-1, st)) return 1;
    FOR (i, 0, n) {
        int nst = (st ^ computed[i]);
        if (i + m < n) nst ^= computed[i+m];
        if (solve(m-1, nst)) return 1;
    }
    return 0;
}

int light;
int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
    cin >> s;
    n = (int)s.length();
    computed.push_back((1<<n)-1);
    FOR (i, 0, n) computed.push_back(computed.back() - (1<<i));
    FOR(i, 0, n) light += (s[i] - '0') * (1<<i);
    FORE (i, 0, 40) if (solve(i, light)) {
        cout << i << endl;
        break;
    }
    return 0;
}