// MagicDark
#include <bits/stdc++.h>
#define debug cerr << "\33[32m[" << __LINE__ << "]\33[m "
#define SZ(x) ((int) x.size() - 1)
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> T& chkmax(T& x, T y) {return x = max(x, y);}
template <typename T> T& chkmin(T& x, T y) {return x = min(x, y);}
template <typename T> T& read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = - f;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	return x *= f;
}
signed main() {
	string st;
	cin >> st;
	int n = st.size(), ans = count(all(st), '1');
	st = ' ' + st;
	F(i, 1, n)
		F(j, i, n) {
			int s = 0;
			F(k, 1, n) {
				if (k < i || k > j) s += st[k] == '1';
				else s += st[k] == '0';
			}
			chkmin(ans, s);
		}
	cout << ans;
	return 0;
}
/* why?
*/