#include <bits/stdc++.h>
using namespace std;

#define F first
#define S second
#define sz(x) (int)x.size()

int main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    string s;
    cin >> s;
    int n = sz(s);
    int ans = 1e9;
    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';
}