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

bool two(int n){
  if(n == 0) return false;
  while(n % 2 == 0){
    n /= 2;
  }
  return n == 1;
}

int main(){
  string s;
  cin >> s;
  if(s.size() == 1) cout << 1 << endl;
  else if(two(s.size()-1)) cout << (s.size()-1)/2 + 1 << endl;
  else cout << (s.size()+1)/2  << endl;
}