#include <bits/stdc++.h>

using namespace std;

/*****************************************************************   Template Start  **************************************************************************/



/*****************************************************************    Define Start   **************************************************************************/
typedef long long                               ll;
typedef unsigned long long                      ull;
#define int                                     long long
#define itn                                     int
#define endl                                    '\n'
#define Endl                                    endl
#define ednl                                    endl
#define al(a)                                   (a).begin(),(a).end()
#define all(a)                                  (a).begin()+1,(a).end()
#define debug(x)                                {cerr<<"ss:"<<x<<endl;}
#define qdebug(x)                               {cerr<<"ss:";for(auto i:x)cout<<i<<" ";cout<<endl;}
#define lowbit(x)                               (x&-x)
#define vi                                      vector<int>
#define pii                                     pair<int,int>
#define pb                                      push_back
#define fs                                      first
#define sc                                      second


constexpr long long maxlonglong = 9223372036854775807;   //9e18
constexpr int maxint = 2147483647;      //2e9
constexpr int INF = 0x7f7f7f7f; //2139062143
constexpr int M = 1e9 + 7;
constexpr int mod =  998244353;
constexpr int p = 0x1F351F35; // good hash number.
const double pi = acos(-1.0);

mt19937_64 rnd(time(0));
constexpr int N=1231564;



inline void solve(){
    string s;cin>>s;
    int n=s.length();
    vi a(n+1);
    for(int i=1;i<=n;i++)a[i]=s[i-1]-'0';
    vi pr(n+2),la(n+2);
    for(int i=1;i<=n;i++)pr[i]=pr[i-1]+a[i];
    for(itn i=n;i;i--)la[i]=la[i+1]+a[i];
    if(pr[n]==0){
        cout<<0<<endl;
        return;
    }
    int ans=INF;
    for(int i=1;i<=n;i++){
        if(a[i]==1)for(int j=i;j<=n;j++){
            if(a[j]==1){
                int cnt=pr[i-1]+la[j+1];
                for(int k=i;k<=j;k++){
                    if(a[k]==0)cnt++;
                }
                ans=min(ans,cnt);
            }
        }
    }
    cout<<ans<<endl;

    




}





signed main()
{
    //freopen("E:\work tool\code document\data\input.in", "r", stdin);
	//freopen("E:\work tool\code document\data\output.out", "w", stdout);
    ios::sync_with_stdio(false);
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);    //关闭同步  如果使用 则不要使用<cstdio>
    // cout << fixed << setprecision(10);
    int T=1;
    // cin>>T;
    while(T--){
        solve();
    }
    return 0;
}