def main():
    import sys
    input = sys.stdin.read().split()
    MOD = 100000000000000007
    
    n = int(input[0])
    m = int(input[1])
    x = list(map(int, input[2:2+m]))
    
    if n == 1:
        print(1)
        return
    
    a = [0] * (n + 1)
    a[1] = 1
    
    for i in range(2, n + 1):
        total = 0
        for xj in x:
            if i - xj >= 1:
                total += a[i - xj]
        a[i] = total % MOD
    
    print(a[n] % MOD)

if __name__ == "__main__":
    main()