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

#define ull unsigned long long
#define ll long long
#define edl '\n'

const int N = 1e6 + 10;
const int M = 1e3 + 10;

const int mod = 1e9 + 7;
ll n,m,q;
string s;


void solve()
{
	ll ans = LLONG_MAX;
	cin >> s;
	for(int i = 0; i < (int)s.length(); i ++ )
	{
		for(int j = i; j < (int)s.length(); j ++ )
		{
			ll sum1 = 0;
			ll sum = 0;
			for(int ii = i; ii <= j; ii ++ )
			{
				if(s[ii] == '1') sum1 ++;
				else sum ++;
			}
			ll g = 0;
			for(int ii = 0; ii < i; ii ++ )
			{
				if(s[ii] == '1') g ++;
			}
			for(int ii = j + 1; ii < (int)s.length(); ii ++ )
			{
				if(s[ii] == '1') g ++;
			}
			ans = min(ans,g + min(sum1,sum));
		}
	}
	cout << ans << edl;
}

int main()
{
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int t = 1;
//	cin >> t;
	while(t -- ) solve();
	return 0;
}