#include <bits/stdc++.h>
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repr(i, a, n) for (int i = n - 1; i >= a; i--)
using namespace std;
using ll = long long;
using P = pair<int, int>;
template <typename T> void chmin(T &a, T b) { a = min(a, b); }
template <typename T> void chmax(T &a, T b) { a = max(a, b); }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  string c;
  cin >> c;
  int n = c.size();

  int ans = 0;
  rep(i, 1, n) {
    string a = c.substr(0, i);
    string b = c.substr(i);
    if (a[0] == '0' || b[0] == '0')
      continue;
    ans++;
  }
  cout << ans << endl;
}