n,m = map(int,input().split())

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

x.sort()

dp = [0 for i in range(n)]

p = 100000000000000007 

for i in range(m):
	dp[x[i]] += 1
	
for i in range(n):
	for j in range(m):
		if i - x[j] >= 0:
			dp[i] += dp[i-x[j]]
			if dp[i] > p:
				dp[i] %= p
			
print(dp[n-1])