cf 279E

int main()
{
    booster()
    //read("input.txt");

    string s;
    cin>>s;
    int sum = 0;
    if(s.size()==1) return cout<<1,0;
    reverse(s.begin(),s.end());
    for(int  i = 0;i <=s.size()-2;){
        if(s[i]=='1'){
            if(s[i+1]=='0') sum++,i++;
            else {
            int l = i;
            while((s[l]=='1')&&(l<s.size()-1)){
                 l++;
            }
            i = l;
            s[i] = '1';
            sum ++;
        }
    }
    else i++;
    }
    sum ++;
    cout<<sum<<endl;

    return 0;
}