#include<bits/stdc++.h>
#define ll long long
#define pii pair<ll,ll>
#define lowbit(x) (x&-x)
#define log(x) (31^__builtin_clz(x))
using namespace std;
int t[55];
void solve(){
	string s;
	cin>>s;
	int n=s.length();
	s=" "+s;
	for(int i=1;i<=n;i++){
		t[i]=s[i]-48;
		t[i]+=t[i-1];
	}
	int ans=n;
	for(int i=1;i<=n;i++){
		for(int j=i;j<=n;j++){
			ans=min(ans,t[i-1]+t[n]-t[j]+(j-i+1-(t[j]-t[i-1])));
		}
	}
	cout<<ans<<"\n";
}
int main(){
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int t=1;
    //cin>>t;
    while(t--)solve();
    return 0;
}