def main():
    N, M = map(int, input().split())
    A = [int(input()) for i in range(M)] + [0]

    a = 0
    b = 1
    j = 0
    tmp = 0
    if N == 1:
        print(1)
    else:
        for i in range(1, N + 1):
            if A[j] == i:
                if tmp == 1:
                    print(0)
                    exit()
                tmp = 1
                j += 1
                a = 0
            else:
                if tmp == 1:
                    b = a + b
                    a = 0
                else:
                    c = a + b
                    a = b
                    b = c
                tmp = 0
        print(c % 1000000007)

if __name__ == '__main__':
    main()
