#include <iostream>

int main() {
    int n;
    while (std::cin >> n) {
        if (!n)
            return 0;
        int currFloor = 0;
        int sum = 0, aim;
        while (n--) {
            std::cin >> aim;
            sum += ((currFloor > aim) ? (4) : (-6)) * (currFloor - aim) + 5;
            currFloor = aim;
        }
        std::cout << sum << std::endl;
    }

    return 0;
}