n = int(input())
a = [int(i) for i in input().split()]

mod = 10**9+7

#print(sum(a)%mod)

ans = 0

wa = [[0 for i in range(n)] for j in range(2)]

for i in range(n):
    wa[0][i] = a[i]
    wa[0][i] %= mod

for i in range(n-1):
    for j in range(n-1-i):
        wa[1][j] = wa[0][j]+wa[0][j+1]
        wa[1][j] %= mod
    wa[0] = wa[1]

print(wa[1][0])