import bisect

MOD = 10**9 + 7

K = int(input())
N = int(input())
x = list(map(int, input().split()))
x.sort()

dp = [0] * (K + 1)
dp[0] = 1  # Base case: 0 steps, 1 way

for k in range(1, K + 1):
    # Find the rightmost index where x[i] <= k
    idx = bisect.bisect_right(x, k) - 1
    total = 0
    for i in range(idx + 1):
        d = x[i]
        if k - d >= 0:
            total += dp[k - d]
            total %= MOD
    dp[k] = total % MOD

print(dp[K] % MOD)