MOD = 10**9 + 7

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

if N == 0:
    print(0)
else:
    total_sum = 0
    current_product = A[0] % MOD
    
    for i in range(1, N):
        a = A[i] % MOD
        new_total = (3 * total_sum + 2 * current_product) % MOD
        new_product = (current_product * a) % MOD
        total_sum, current_product = new_total, new_product
    
    result = (total_sum + current_product) % MOD
    print(result)