mod = 1000000007
k = int(input())
n = int(input())
X = list(map(int, input().split()))
li = [0] * (k + 1)
li[0] = 1
for i in range(1, k + 1):
    for j in X:
        if i < j:
            break
        li[i] = (li[i] + li[i - j]) % mod
print(li[k] % mod)