n,m = map(int,input().split())
ab = []
for _ in range(m):
    a=int(input())
    ab.append(a)

dp = [0]*(n+1)
dp[0] = 1

for i in range(1, n+1):
    dp[i] = (dp[i-1] + dp[i-2])%1000000007
    if i in ab:
        dp[i] = 0

print(dp[-1])