#include <bits/stdc++.h>

using namespace std;

typedef long long i64;
const int inf = 1e9;

typedef long long i64;

void solve() {
    string s;
    cin >> s;
    int n = (int) s.size();
    vector<int> ones;
    for (int i = 0; i < n; ++i) {
        if (s[i] == '1') {
            ones.push_back(i);
        }
    }
    int ans = (int) ones.size();
    for (size_t l = 0; l < ones.size(); ++l) {
        for (size_t r = l; r < ones.size(); ++r) {
            int cnt = ones.size() - int(r - l + 1);
            for (int i = ones[l]; i <= ones[r]; ++i) {
                cnt += (s[i] == '0') ? 1 : 0;
            }
            ans = min(ans, cnt);
        }
    }
    cout << ans << "\n";
}

signed main() {
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
#endif
    ios_base::sync_with_stdio(false);
    int t = 1;
    // cin >> t;
    while (t --> 0) {
        solve();
    }
    return 0;
}