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

int main()
{
    string s;
    cin >> s;
    cout << int((log10(s[0] - '0') + s.size()-1)/2 + 1) << endl;
    return 0;
}