#include "bits/stdc++.h"
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = (ll)1e9 + 7;



signed main() {
	string N; cin >> N;
	int tmp = N.size();
	cout << (tmp + 1) / 2 << endl;
}