#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int n;
ll X;
ll FULL;
int sol = 6;

unordered_set<ll> M;

void solve(ll state, int depth) {
  if (depth > 5) return;
  if ((state ^ FULL) == 0) {
    sol = min(sol, depth);
    return;
  }
  if (M.find(state) != M.end()) return;
  M.insert(state);

  for (int i=1; i<n; i++)
    solve(state | (state >> i), depth+1);
}

int main() {
  string s;
  cin >> s;
  n = s.size();
  for (int i=0; i<n; i++)
    X += (1LL << (n-i-1)) * (s[i] == '1');
  FULL = (1LL << n) - 1;

  // cout << X << " " << FULL << endl;

  if (s[0] != '1') {
    cout << -1 << endl;
    return 0;
  }

  solve(X, 0);

  cout << sol << endl;

  return 0;
}