K=int(input())
N=int(input())
X=list(map(int,input().split()))
mod=10**9+7

#X.sort()

DP=[0]*(K+1)
DP[0]=1

for i in range(K):
    if DP[i]==0:
        continue

    for j in range(N):
        if X[j]+i<=K:
            DP[X[j]+i]=(DP[i]+DP[X[j]+i])%mod

        else:
            break

print(DP[-1])