K = int(input())
N = int(input())
X = list(map(int, input().split()))
dp = [0]*K
mod = 10**9 + 7
for x in X:
    if x < K:
        dp[x-1] = 1

for j in range(K):
    for x in X:
        if 0 <= j-x < K:
            dp[j] += dp[j-x]
            dp[j] %= mod

print(dp[-1]%mod)