#include<bits/stdc++.h>
#define int long long
#define db double
#define ll long long
#define pii pair<int, int>
using namespace std;
void solve() {
    string str;
    cin >> str;
    int n = str.length();
    str = '#' + str;
    int ans = 1e9;
    for (int i = 1; i <= n; i++)
        for (int j = i; j <= n; j++) {
            if (i == 4 && j == 8)
                int debug = 0;
            int tem = 0;
            for (int k = i; k <= j; k++)
                tem += str[k] == '0';
            for (int k = 1; k < i; k++)
                tem += str[k] == '1';
            for (int k = j + 1; k <= n; k++)
                tem += str[k] == '1';
            ans = min(ans, tem);
        }
    cout << ans << "\n";
}
signed main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}