N = int(input())
A = list(map(int, input().split()))
X = (10 ** 9) + 7

for i in range(N-1):
    x = [None] * (N - i - 1)
    for i in range(N - i - 1):
        x[i] = A[i] + A[i+1]
    A = x

print(sum(A) % X)