n,m = map(int,input().split())
l = [1]*n
#kubaru_dp = [1]*n

for i in range(m):
    a = int(input())
    l[a] = 0

# l = [1,1,1,0,1,1,1]
for i in range(2,n+1):
    if l[i]==0:
        continue
    l[i] = l[i-1]+l[i-2]
else:
    print(l[-1]%(10**9+7))
