#include <iostream>
#include <cstdio>
#include <vector>

using namespace std;

typedef long long LL;
typedef pair<int, int> PII;

const int N = 200010;

string s;
vector<PII> vec;
LL cost[N], gap[N], ps[N], f[N];

int main() {
    // freopen("apple.in", "r", stdin);
    // freopen("apple.out", "w", stdout);

    cin >> s;

    int n = s.size();
    s = ' ' + s;
    for (int l = 1; l <= n; ) {
        while (l <= n && s[l] == '0') ++l;
        if (l > n) break;
        int r = l;
        while (r < n && s[r + 1] == s[l]) ++r;
        vec.push_back({ l, r });
        l = r + 1;
    }
    if (vec.empty()) {
        puts("0");
        return 0;
    }

    for (int i = 0; i < vec.size(); ++i) {
        cost[i] = min(2, vec[i].second - vec[i].first + 1);
    }
    for (int i = 1; i < vec.size(); ++i) {
        gap[i] = vec[i].first - vec[i - 1].second - 1;
        ps[i] = ps[i - 1] + gap[i];
    }

    LL best = 0LL;
    f[0] = cost[0];
    for (int i = 1; i < vec.size(); ++i) {
        best = min(best, f[i - 1] - ps[i]);
        f[i] = f[i - 1] + cost[i];
        f[i] = min(f[i], best + ps[i] + 2);
    }

    printf("%lld\n", f[vec.size() - 1]);

    return 0;
}