MOD = 10 ** 9 + 7

def convert(A):
    N = len(A)
    ret = [0 for i in range(N - 1)]
    for i in range(N - 1):
        ret[i] = A[i] + A[i + 1]
    return ret

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

for i in range(N - 1):
    A = convert(A)
print(A[0] % MOD)