import itertools,sys
def I(): return int(sys.stdin.readline().rstrip())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
N,M = LI()
a = set([I() for _ in range(M)])
dp = [0]*(N+1) #1_indexed
dp[0] = 1
dp[1] = 0 if 1 in a else 0
for i in range(2,N+1):
    if i in a:
        dp[i] = 0
        continue
    dp[i] = (dp[i-1]+dp[i-2])%(10**9+7)
print(dp[-1])
