import bisect

MOD = 10**9 + 7

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

# Find valid step sizes up to K
idx = bisect.bisect_right(x, K)
valid_x = x[:idx]
m = len(valid_x)

if m == 0:
    print(0)
    exit()

dp = [0] * (K + 1)
dp[0] = 1  # Base case: one way to be at step 0

for i in range(1, K + 1):
    # Find the number of valid steps that are <= i
    j_max = bisect.bisect_right(valid_x, i)
    total = 0
    for j in range(j_max):
        total += dp[i - valid_x[j]]
        if total >= MOD:
            total -= MOD
    dp[i] = total % MOD

print(dp[K] % MOD)