#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
using ull = unsigned long long;
#define ff(x) fixed << setprecision(x)
#define vel vector<long long>
#define vei vector<int>
#define ves vector<string>
#define asn ans
constexpr int inf = 0x3f3f3f3f;
constexpr ll INF = 0x3f3f3f3f3f3f3f3fLL;
constexpr db EPS = 1.0e-9;
constexpr ll MOD = 998244353LL;
constexpr ll SZ = 1e6;
constexpr ll MAXN5 = 2e5 + 5;
constexpr ll MAXN6 = 2e6 + 5;
ll n, m;

void Solve(void) {
    string s;
    cin >> s;
    ll a[s.size() + 1];
    fill(a, a + s.size() + 1, 0);
    vector<int> xia;
    for (int i = 0; i < s.size(); i++) {
        if (s[i] == '1') {
            a[i + 1] = 1;
            xia.push_back(i + 1);
        }
    }
    if (a[s.size()] == s.size() || a[s.size()] == 0) {
        cout << 0;
        return;
    }
    for (int i = 1; i <= s.size(); i++) {
        a[i] += a[i - 1];
    }
    int ans = INT_MAX;
    // for(auto x:xia){
    //     cout<<x<< ' ' ;
    //     cout<<a[x]<<'\n';
    // }
    for (int i = 0; i < xia.size(); i++) {
        for (int j = i + 1; j < xia.size(); j++) {
            int zuo = a[xia[i] - 1] - a[0];
            int you = a[s.size()] - a[xia[j]];
            int mid = xia[j] - xia[i] + 1 + a[xia[i] - 1] - a[xia[j]];
         //   cout << zuo << ' ' << you << ' ' << mid << '\n';
            ans = min({ans, zuo + you + mid, (int)s.size()});
        }
    }
    cout << ans;
}
int main(void) {
    ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    // 	freopen("mine.in", "r", stdin);
    // 	freopen("mine.out", "w", stdout);

    int cas = 1;
    // cin >> cas;
    while (cas--)
        Solve();
    return 0;
}