#include <iostream>
using namespace std;

int main()
{
    int x;

    int t = 1, ans = 0;
    while (cin >> x, x)
    {
        if (x == 1) 
            t = 1;
        else if (x == 2)
        {
            if (t % 2 == 0) t += 2;
            else t = 2;
        }

        ans += t;
    }

    cout << ans << endl;
}