MOD = 10**9 + 7

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

# Since x is already sorted as per the problem statement
dp = [0] * (K + 1)
dp[0] = 1

for k in range(1, K + 1):
    # Find the rightmost index where x[i] <= k using bisect_right
    left, right = 0, N
    while left < right:
        mid = (left + right) // 2
        if x[mid] <= k:
            left = mid + 1
        else:
            right = mid
    idx = left
    # Iterate through all x_i <= k
    for i in range(idx):
        xi = x[i]
        if k - xi >= 0:
            dp[k] = (dp[k] + dp[k - xi]) % MOD

print(dp[K] % MOD)