#include<bits/stdc++.h>
using namespace std;
const int N=1919810;
typedef int ll;
typedef pair<ll,ll> PII;
int n,m,k;
ll a[N],b[N];
char s[N];

void __(){
    scanf("%s",s+1);
    n=strlen(s+1);
    vector<PII> v;
    int now=s[1]-'0';
    int cnt=0;
    for(int i=1;i<=n;i++){
        int t=s[i]-'0';
        if(t==now){
            cnt++;
        }else{
            v.push_back({now,cnt});
            cnt=1;
            now=t;
        }
    }
    v.push_back({now,cnt});
    int ans=n+1;
    int now1=0,now2=0;
    bool flag=0;
    for(int i=0;i<v.size();i++){
        int t=v[i].first;
        now1+=v[i].second;
        if(t==1){
            flag=1;
            ans=min(ans,n-now1+now2);
        }else{
            ans=min(ans,n-now1+now2);
            if(flag) now2+=v[i].second;
        }
    }
    int cnt1=0;
    for(auto [x,y]:v) if(x==1) cnt1+=y;
    // cout<<cnt1<<endl;
    for(auto [x,y]:v){
        // cout<<x<<" "<<y<<endl;
        if(x==1){
            ans=min(ans,cnt1-y);
        }
    }
    cout<<ans<<endl;
}


int main(){
    int _=1;
    // cin>>_;
    while(_--){
        __();
    }
}