#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define sc scanf
#define dl double
#define pr printf
long long gcd(long long a, long long b)
{
    if (a < b)
        swap(a, b); // 如果b大的话就交换值 让b%a
    if (b == 0)     // 除到最后 如果返回的值是1 说明两个数互质
        return a;
    else
        return gcd(a % b, b);
}
long long mod_inv(long long x, long long mod)
{
    long long result = 1;
    long long power = mod - 2;
    while (power > 0)
    {
        if (power % 2 == 1)
        {
            result = (result * x) % mod;
        }
        x = (x * x) % mod;
        power /= 2;
    }
    return result;
}
int main(){
    string a;
    cin >> a;
    ll cnt = a.length();
    a = ' ' + a;
    ll pre[100];
    pre[0] = 0;
    for (ll i = 1; i <= cnt;i++){
        pre[i] = pre[i - 1];
        if(a[i]=='1'){
            pre[i]++;
        }
    }
    ll ans = min(pre[cnt], cnt - pre[cnt]);
    for (ll i = 1; i <= cnt;i++){
        for (ll j = i; j <= cnt;j++){
            ll x = j - i + 1 - pre[j] + pre[i - 1] + pre[cnt] - pre[j] + pre[i - 1];
            ans = min(ans, x);
        }
    }
    cout << ans;
    return 0;
}