#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

int main() {
    string C;
    cin >> C;
    int ans = 0;
    rep(i, C.size() - 1) {
        if (C[i + 1] != '0') ans++;
    }
    cout << ans << "\n";
}