#include <iostream>
using namespace std;
int main(){
int n, ans = 0;
cin >> n;
int last = 0;
for(int i = 1; i <= n; ++i){
int x;
cin >> x;
if(x & last){
++ans;
last = 0;
}
else{
last = x;
}
}
cout << ans;

return 0;
}