1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define maxn 10000000
 4 
 5 int a[maxn],ans;
 6 char s[maxn];
 7 int main()
 8 {
 9     cin>>s;
10     for(int i=0;i<strlen(s);i++) a[i+1]=s[i]-‘0‘;
11     int n=strlen(s);
12     while(n)
13     {
14         if(a[n]==0) 
15         {
16             ans++;
17             for(int i=n;i>=1;i--) a[i]=a[i]^1;
18         }
19         n--;
20     }
21     
22     printf("%d",ans);
23     return 0;
24 }