//by 72
#include<bits/stdc++.h>
#define F(i, a, b) for(int i = a; i <= b; i ++)
#define Fd(i, a, b) for(int i = a; i >= b; i --)
#define pb push_back
#define pii pair<int, int>
#define fi first
#define se second
#define int long long
using namespace std;

const int mod = 998244353;
const int N = 2e5 + 10;
const int inf = 1e18;
typedef array<int, 3> a3; 
typedef long long ll;

int n, m, a[N];

void sol() {
    string s; cin >> s;
    n = s.size();
    s = " " + s;
    F(i, 1, n) a[i] = a[i - 1] + (s[i] == '1');
    int res = a[n];
    F(i, 1, n) F(j, i, n) if(s[i] == '1' && s[j] == '1')
        res = min(res, a[i - 1] + a[n] - a[j] + (j - i + 1 - (a[j] - a[i - 1]))); 
    cout << res << "\n";
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int t = 1;
    F(i, 1, t) sol();
    return 0;
}
//sldl