#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
#define range(x) (x).begin(), (x).end()
const int dir[][2] = {1, 0, -1, 0, 0, 1, 0, -1};

void solve()
{
    string s;
    cin >> s;
    int n = s.size();
    if (count(range(s), '1') == 0) {
        cout << "0\n";
        return;
    }
    int ans = n;
    for (int i = 0; i < n; ++i)
        for (int j = i; j < n; ++j) {
            int cnt = 0;
            for (int k = 0; k < n; ++k) {
                if (k < i || k > j)
                    cnt += (s[k] == '1');
                else
                    cnt += (s[k] == '0');
            }
            ans = min(ans, cnt);
        }

    cout << ans << '\n';
}

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

    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}