#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

int diff(string a, string b){
   //2進数表示で、aからbの引き算してから、結果に含まれる1の個数を調べる
  
  deque<char> q;

  int pa = (int)a.size()-1; int pb = (int)b.size()-1;
  int k = 0; //k == 1で、すでに借りがある状態。なければ0.
  for(int i = 0; i < pa-pb; i++){ b = "0" + b;}  //桁を揃える
  int p = pa;
  while( p >= 0){
    if( k == 0){
     if( a[p] == '0' && b[p] == '0'){ q.push_front('0');}
     if( a[p] == '0' && b[p] == '1'){ q.push_front('1'); k = 1;}
     if( a[p] == '1' && b[p] == '0'){ q.push_front('1');}
     if( a[p] == '1' && b[p] == '1'){ q.push_front('0');}
    }
    else{//借りを残している場合
     if( a[p] == '0' && b[p] == '0'){ q.push_front('1');}//まだ借りは残る
     if( a[p] == '0' && b[p] == '1'){ q.push_front('0');}
     if( a[p] == '1' && b[p] == '0'){ q.push_front('0'); k = 0;}
     if( a[p] == '1' && b[p] == '1'){ q.push_front('1');}
    }
    p--;
  }
   int cnt = 0;
    for(int i = 0; i < (int) q.size(); i++){ if(q[i] == '1'){ cnt++;}}
  
   
  return cnt;
}
  
int main(){
  string S; cin >> S;
  int N = (int) S.size();
  
  string M = "1"; string m = "1";
  for(int i = 0; i < N; i++){ M += "0";}
  for(int i = 0; i < N-1; i++){ m += "0";}
  
  int res1 = diff(M,S); int res2 = diff(S,m);

  cout << min(res1,res2)+1 << endl;
  
  
  return 0;}