#include <bits/stdc++.h>
using namespace std;

string N;
int l, n, ans;

void Solve(int n, int c, int maxc) {
	if (n == 1) {ans += maxc + 1; return;}
	Solve((n + 1) >> 1, c + 1, max(maxc, c + 1));
	Solve(n >> 1, 0, maxc);
	return;
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
	cin >> N; l = N.length();
	for (int i = 0; i < l; ++i) n = n << 1 | (N[i] == '1');
	Solve(n, 0, 0);
	cout << ans << "\n";
	return 0;
}