#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
const int INF=1e9+7;
int main()
{
	string s; cin>>s;
	s="00"+s;
	int n=s.size();
	int dp[2][200020];
	dp[0][0]=0;
	dp[1][0]=INF;
	for(int i=1; i<n; i++){
		dp[0][i]=min(dp[1][i-1]+1, dp[0][i-1])+s[i]-'0';
		int d=2;
		dp[1][i]=min(dp[1][i-1], dp[0][i-1]+1)+d-1-(s[i]-'0');
	}
	cout<<min(dp[0][n-1], dp[1][n-1]+1)<<endl;
	return 0;
}