N=int(input())
li=list(map(int,input().split()))
mod=10**9+7
for i in range(N-1):
    li2=[0 for j in range(N-1-i)]
    for j in range(N-1-i):
        li2[j]=(li[j]+li[j+1])%mod
    li=li2
print(li[0]%mod)