#include <fstream>
int a[100005];
long long n;
using namespace std;

int main()
{
    int i,contor;
    ifstream fin ("and.in");
    ofstream fout ("and.out");
    fin>>n;
    a[1]=1;
    contor=0;
    for(i=1;i<=n;i++)
      fin>>a[i];
    for(i=1;i<=n;i++)
        if(a[i] & a[i+1]!=0){a[i+1]=a[i+2];contor++;}
        else a[i]=a[i+1];
    fout<<contor;
    fin.close();
    fout.close();
    return 0;
}