import bisect

MOD = 10**9 + 7

def main():
    import sys
    input = sys.stdin.read().split()
    ptr = 0
    K = int(input[ptr])
    ptr += 1
    N = int(input[ptr])
    ptr += 1
    x = list(map(int, input[ptr:ptr+N]))
    ptr += N
    x.sort()  # Ensure x is sorted, though input says it is
    
    dp = [0] * (K + 1)
    dp[0] = 1
    pre = [0] * (K + 1)
    pre[0] = dp[0]
    
    for i in range(1, K + 1):
        # Find the largest x_j <= i
        m = bisect.bisect_right(x, i) - 1
        if m < 0:
            s = 0
        else:
            s = 0
            for j in range(m + 1):
                k = i - x[j]
                if k >= 0:
                    s += dp[k]
                    if s >= MOD:
                        s -= MOD
        dp[i] = s % MOD
        pre[i] = (pre[i - 1] + dp[i]) % MOD
    
    print(dp[K] % MOD)

if __name__ == "__main__":
    main()