import sys


n, m = [int(_) for _ in input().split()]
l = []
for i in range(m):
    l.append(int(input()))

d = [0] * (n + 2)
d[0] = 1
if 1 not in l:
    d[1] = 1
for i in range(n):
    if i in l and i + 1 in l:
        print(0)
        sys.exit()
    elif i in l:
        d[i + 2] = d[i + 1]
    elif i + 1 in l:
        d[i + 2] = d[i]
    else:
        d[i + 2] = d[i] + d[i + 1]
    d[i + 2] = d[i + 2] % (10 ** 9 + 7)
print(d[-2])