n,m = map(int, input().split())
bl = set([int(input())-1 for _ in range(m)])
l = [i for i in range(n)]

mod = 1000000007
al = [0]*n
if 0 in l and 1 in l:
    al[0] = 1
    al[1] = 2
elif 0 in l:
    al[0] =1
elif 1 in l:
    al[1] = 1
else:
    print(0)
    exit()

    
li = [i for i in l if i>=2]

for i in li:
    if i not in bl:
        al[i] = (al[i-1] + al[i-2])%mod
        if al[i] == 0:
            print(0)
            exit()

print(al[-1])
