fibonacci_last_digit_large_number

# Uses python3
import sys

# too slow memory exceeded
def get_fibonacci_last_digit_naive(n):
    if n <= 1:
        return n

    previous = 0
    current = 1

    for _ in range(n - 1):
        previous, current = current, previous + current

    return current % 10

# faster solution only storing the last digit
def fib_last_digit_large_number(n):
    if n <= 1:
        return n

    l = [0, 1]
    i = 2

    while i < n + 1:
        # stores only the last unit digit of every number which turns out is all you need
        # to compute the next addition
        l.append((l[i - 1] + l[i - 2]) % 10)
        i += 1

    return l[n]


if __name__ == '__main__':
    # user_input = sys.stdin.read()
    n = int(input())
    print(fib_last_digit_large_number(n))