The numbers of all offices in the new building of the Tax Office of IT City will have lucky numbers.

Lucky number is a number that consists of digits 7 and 8 only. Find the maximum number of offices in the new building of the Tax Office given that a door-plate can hold a number not longer than *n* digits.
The only line of input contains one integer *n* (1 ≤ *n* ≤ 55) — the maximum length of a number that a door-plate can hold.
none
2
6
1
2
3
14
5
62
12
8190
34
34359738366
43
17592186044414
49
1125899906842622
54
36028797018963966
55
72057594037927934
# The numbers of all offices in the new building of the Tax Office of IT City will have lucky numbers.
# Lucky number is a number that consists of digits 7 and 8 only. Find the maximum number of offices in the new building of the Tax Office given that a door-plate can hold a number not longer than n digits.

# n la cantidad de digitos, 1 <= n <= 55
# n = 2
# 7, 8, 77, 88, 78, 87  => 6

# 787878887 :)
# 20830128320 :(

n = int(input()) 

# a_1  a_2  a_3 .... a_n  ¿Cuantos números de la suerte hay de n cifras?
# 2  2  2 .... 2 

# n = 3
# Los 1 digito => 2 (7, 8)
# Los 2 digitos => 4
# Los 3 digitos => 8   Y sumar  2 + 4 + 8 = 14

# Sumar 2^1, 2^2, ..., 2^n

suma = 0
for i in range(1, n+1):  # 1 -> n
    suma += 2**i

print(suma)