#include <map>
#include <set>
#include <array>
#include <cmath>
#include <deque>
#include <bitset>
#include <random>
#include <string>
#include <vector>
#include <cassert>
#include <complex>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>

using namespace std;


int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  string s;
  cin >> s;
  int n = s.size();
  vector<int> p(n + 1);
  for (int i = 1; i <= n; ++i) {
    p[i] = p[i - 1] + (s[i - 1] == '1');
  }

  int ans = n;
  for (int i = 0; i < n; ++i) {
    for (int j = i; j <= n; ++j) {
      ans = min(ans, p[i] + (j - i - (p[j] - p[i])) + p[n] - p[j]);
    }
  }
  cout << ans << '\n';


  return 0;
}