import sys
from collections import defaultdict

inputs = sys.stdin.readline


def main():
    N = int(inputs())
    A = list(map(int, inputs().split()))
    dic = defaultdict(int)
    for a in A:
        dic[a] += 1
    ans = 0
    for i in range(1, 9):
        for j in range(1, 9):
            val = i ** j
            cnt = dic[i] * dic[j]
            ans += val * cnt
    print(ans)


if __name__ == "__main__":
    main()