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

dp = [[0] * N for _ in range(N)]
for i in range(N):
    dp[0][i] = A[i]
for i in range(N-1):
    for j in range(N-1-i):
        dp[i+1][j] = (dp[i][j] + dp[i][j+1]) % P
print(dp[N-1][0])