n = int(input())
A = list(map(int, input().split()))

N = [0 for _ in range(9)]
for i in range(n):
    N[A[i]] += 1
ans = 0
for i in range(1, 9):
    for j in range(i, 9):
        if i == j:
            ans += N[i]**2 * i**j
        else:
            ans += N[i] * N[j] * (i**j + j**i)
print(ans)