#include<bits/stdc++.h>

using namespace std;

#define int long long
#define pb push_back
#define F first 
#define S second 

const int mol=998244353;

void solve(){
    string a;
    cin>>a;
    int to=0;
    for(auto t: a) to+=(t=='1');
    int ans=to;
    for(int i=0;i<a.size();i++){
        int t1=0, t0=0;
        for(int j=i;j<a.size();j++){
            if(a[j]=='0') t0++;
            else t1++;
            ans=min(ans, t0+to-t1);
        }
    }
    cout<<ans<<"\n";
}


signed main(){
    ios::sync_with_stdio(0);cin.tie(0);
    // int t;
    // cin>>t;
    // while(t--)
    solve();
    return 0;
}