#include<bits/stdc++.h>
using namespace std;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
const int INF=1e9;

int main()
{
    string s; cin>>s;
    int N=s.size();
    reverse(s.begin(),s.end());

    vector<int> dp0(N+1,INF);
    vector<int> dp1(N+1,INF);
    dp0[0]=0;

    for(int i=0;i<N;i++){
        if(s[i]=='0'){
            chmin(dp0[i+1],dp0[i]);
            chmin(dp0[i+1],dp1[i]+1);
            chmin(dp1[i+1],dp1[i]+1);
        }else{
            chmin(dp0[i+1],dp0[i]+1);
            chmin(dp1[i+1],dp0[i]+1);
            chmin(dp1[i+1],dp1[i]);
        }
    }
    cout<<min(dp0[N],dp1[N]+1)<<endl;
    return 0;
}