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

m = 1000000007

t = A[:]
n = []
while len(t) != 1:
    for i in range(len(t) - 1):
        n.append((t[i] + t[i + 1]) % m)
    t = n
    n = []
print(t[0])