P13301.py

cache = [0, 4, 6, 10, 16, 26, 42, 68, 110, 178, 288, 466, 754, 1220, 1974, 3194, 5168, 8362, 13530, 21892, 35422, 57314,
         92736, 150050, 242786, 392836, 635622, 1028458, 1664080, 2692538, 4356618, 7049156, 11405774, 18454930,
         29860704, 48315634, 78176338, 126491972, 204668310, 331160282, 535828592, 866988874, 1402817466, 2269806340,
         3672623806, 5942430146, 9615053952, 15557484098, 25172538050, 40730022148, 65902560198, 106632582346,
         172535142544, 279167724890, 451702867434, 730870592324, 1182573459758, 1913444052082, 3096017511840,
         5009461563922, 8105479075762, 13114940639684, 21220419715446, 34335360355130, 55555780070576, 89891140425706,
         145446920496282, 235338060921988, 380784981418270, 616123042340258, 996908023758528, 1613031066098786,
         2609939089857314, 4222970155956100, 6832909245813414, 11055879401769514, 17888788647582928, 28944668049352442,
         46833456696935370, 75778124746287812, 122611581443223182, 198389706189510994, 321001287632734176,
         519390993822245170, 840392281454979346, 1359783275277224516, 2200175556732203862, 3559958832009428378,
         5760134388741632240, 9320093220751060618, 15080227609492692858, 24400320830243753476, 39480548439736446334,
         63880869269980199810, 103361417709716646144, 167242286979696845954, 270603704689413492098,
         437845991669110338052, 708449696358523830150, 1146295688027634168202]


def gen():
    c = [None for x in range(100)]
    d = [None for x in range(100)]

    def fibonacci(n):
        if c[n] is not None:
            return c[n]

        if n <= 2:
            return 1
        else:
            res = fibonacci(n - 1) + fibonacci(n - 2)
            c[n] = res
            return fibonacci(n - 1) + fibonacci(n - 2)

    def new_fibonacci(n):
        fib_init = [0, 4, 6, 10]
        if n < 4:
            return fib_init[n]

        if d[n] is None:
            d[n] = fibonacci(n) * 3 + fibonacci(n - 1) * 2 + fibonacci(n - 2) * 2 + fibonacci(n - 3)

        return d[n]

    fib_arr = []
    n_fib_arr = []
    for i in range(100):
        fib_arr.append(fibonacci(i))

    for i in range(100):
        n_fib_arr.append(new_fibonacci(i))

    print(fib_arr)
    print(n_fib_arr)


if __name__ == '__main__':
    # gen()
    print(cache[int(input())])