n, m = map(int,input().split())
hole = [int(input()) for _ in range(m)]
k = 0
a, b = 0, 0
x = (10 ** 9 + 7)
for i in range(n):
    if i + 1 == hole[k]:
        a, b = 0, a
    else:
        if i == 0:
            a = 1
        elif i == 1:
            a, b = (a + 1) % x, a % x
        else:
            a, b = (a + b) % x, a % x
    if i + 1 >= hole[k] and k < m - 1:
        k += 1

    
print(a)