#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (long long i = 0; i < (n); ++i)
using ll = long long;
using P = pair<ll,ll>;
using PP = pair<P,ll>;
using vec = vector<ll>;
using vecp = vector<P>;
using mat = vector<vec>;
using matp = vector<vecp>;
const ll MOD = 1e9+7;
const ll INF = 1e18;
#define all(v) v.begin(), v.end()




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