#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
#define X first
#define Y second
#define umap unordered_map
using ll = long long;
using ull = unsigned long long;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int maxn = 2e5 + 5, mod = 1e9 + 7, maxp = 31, inf = 1e9;
const ll INF = 1e18;
const double eps = 1e-6;

void solve() {
	string s;
	cin >> s;
	const int n = s.size();
	int ans = n;
	for (int l = 0; l < n; l++) {
		for (int r = l; r < n; r++) {
			int cnt = 0;
			for (int i = 0; i < n; i++) {
				if (i >= l && i <= r) {
					if (s[i] == '0') cnt++;
				}
				else {
					if (s[i] == '1') cnt++;
				}
			}
			ans = min(ans, cnt);
		} 
	}

	cout << ans << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int tt = 1;
    // cin >> tt;
    while (tt--) solve();
    return 0;
}