#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")


constexpr int N = 128;
// n, mex, amari -> score
int dp[N + 1][N + 1][N + 1];

int main() {
  memset(dp, ~0, sizeof(dp));
  dp[1][0][1] = 0;
  dp[1][1][0] = 1;
  for (int n = 2; n <= N; ++n) {
    auto check = [&](int n0, int n1) -> void {
      vector<int> fs1(n1 + 1, -1);
      for (int a1 = 0; a1 <= n1; ++a1) for (int b1 = 0; b1 <= n1; ++b1) {
        chmax(fs1[b1], dp[n1][a1][b1]);
      }
      for (int a0 = 0; a0 <= n0; ++a0) for (int b0 = 0; b0 <= n0; ++b0) if (~dp[n0][a0][b0]) {
        for (int b1 = 0; b1 <= n1; ++b1) if (~fs1[b1]) {
          for (int a = a0; a <= a0 + b0 + b1; ++a) {
            chmax(dp[n][a][b0 + b1 - (a - a0)], a + dp[n0][a0][b0] + fs1[b1]);
          }
        }
      }
    };
    check(n/2, n - n/2);
    if (n/2 != n - n/2) check(n - n/2, n/2);
  }
  for (int n = 1; n <= N; ++n) {
    int mx = -1;
    int am = -1, bm = -1;
    for (int a = 0; a <= n; ++a) for (int b = 0; b <= n; ++b) {
      if (chmax(mx, dp[n][a][b])) {
        am = a;
        bm = b;
      }
    }
    cerr << n << " " << am << " " << bm << ": " << mx << endl;
  }
  
  char S[10];
  for (; ~scanf("%s", S); ) {
    int n = 0;
    for (char *s = S; *s; ++s) (n <<= 1) |= (*s - '0');
    int ans = 0;
    for (int a = 0; a <= n; ++a) for (int b = 0; b <= n; ++b) chmax(ans, dp[n][a][b]);
    printf("%d\n", ans);
  }
  return 0;
}