from fractions import gcd
from datetime import date, timedelta
from heapq import*
import math
from collections import defaultdict, Counter, deque
import sys
from bisect import *
import itertools
import copy
sys.setrecursionlimit(10 ** 7)
MOD = 10 ** 9 + 7


def main():
    n = int(input())
    p = list(map(int, input().split()))
    v = 1


    def f(s):
        ret = 0
        for i in range(len(str(v))):
            ret += int(str(v)[i])
        return str(ret)
    t = 1
    for i in range(n):
        v = str(p[i])
        while True:
            s = f(v)
            if len(s) == 1:
                #print(s)
                break
            v = s
        t *= int(s)
    t = str(t)
    while True:
        s = f(t)
        if len(s) == 1:
            print(s)
            break
        v = s
    



    


if __name__ == '__main__':
    main()