#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=1e5+5;
inline int read(){
	int x=0,f=1;char ch=getchar_unlocked();
	while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar_unlocked();}
	while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-48,ch=getchar_unlocked();}
	return x*f;
}
int n,sum[N];
string s;
signed main(){
	// freopen("love.in","r",stdin);
	// freopen("love.out","w",stdout);
	cin>>s;
	n=s.size();
	s=' '+s;
	int ans=1e18;
	for(int i=1;i<=n;i++) sum[i]=sum[i-1]+(s[i]=='1');
	for(int i=1;i<=n;i++){
		for(int j=i;j<=n;j++){
			int res=j-i+1-(sum[j]-sum[i-1]);
			res+=(sum[i-1]);
			res+=(sum[n]-sum[j]);
			ans=min(ans,res);
		}
	} 
	cout<<ans;
	return 0;
}