#include <stdio.h>
 
int main() {
    int tombol;
    long long kelereng = 0;
    while (1) {
        scanf("%d", &tombol);
        if (tombol == 9) {
            break;
        } else if (tombol == 1) {
            kelereng += 1;
        } else if (tombol == 2) {
            if (kelereng % 2 == 0) {
                kelereng = kelereng / 2;
            } else {
                kelereng = kelereng * 2;
            }
        }
    }
 
    printf("%lld\n", kelereng);
    return 0;
}