#include <bits/stdc++.h>

using namespace std;

void solve(){
    string s; cin >> s; int n = s.size(); s = ' ' + s;
    vector <int> pref(n + 1, 0); int ans = n;
    for (int i = 1; i <= n; ++ i){
        pref[i] = pref[i - 1] + (s[i] - '0');
    }
    for (int l = 1; l <= n; ++ l) for (int r = l; r <= n; ++ r) ans = min(ans, r - l + 1 - pref[r] + pref[l - 1] + pref[n] - pref[r] + pref[l - 1]);
    cout << ans;
}

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

    solve();

    return 0;
}