#include <bits/stdc++.h>

#define speed ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define ll long long
#define YES "Yes"
#define NO "No"
#define endline '\n'

using namespace std;

const ll N = 5e5 + 10, MM = 998244353, MAX = 1e18;

int n;
string s;

ll solve1(int l,int r){
  ll res=0;
  for(int i=0;i<n;i++){
    if(i>=l&&i<=r){
      if(s[i]=='0')res++;
    }else{
      if(s[i]=='1')res++;
    }
  }
  return res;
}

int solve() {
  cin>>s;
  n=s.size();
  if(s==string(n,'0'))return cout<<0<<endline,0;
  ll res=n;;
  for(int i=0;i<n;i++){
    for(int j=i;j<n;j++){
      res=min(res,solve1(i,j));
    }
  }
  cout<<res<<endline;
  return 0;
}

int main() {
	speed;
	int t = 1;
	//cin >> t;
	int i = 1;
	while (t--) {
		//cout << "Case #" << i++ << ": ";
		solve();
	}
	return 0;
}
/*


*/