n=int(input())
a=[*map(int,input().split())]
mod=10**9+7
while len(a)>1:
    n=len(a)
    b=[0]*(len(a)-1)
    for i in range(1,n):
        b[i-1]=a[i-1]+a[i]
    a=b
print(a[0]%mod)