#include<iostream>
#include<cstring>
#include<cstdio>
#include<string>
#include<algorithm>
using namespace std;

string s;

int main()
{
    while(cin >> s)
    {
        int len = s.length();
        int ans = 0,flag = 0;
        for(int now = 0;now < len;now++)
        {
            if(flag)
            {
                while(now < len)
                {
                    if(s[now] == ‘1‘)
                    {
                        ans++;
                        flag = 0;
                        break;
                    }
                    else    now++;
                }
            }
            else if(s[now] == ‘0‘)    flag = 1;
        }
        if(flag)    ans++;
        printf("%d\n",ans);
    }
    return 0;
}