n, m = (int(x) for x in input().split())
ab = []
for _ in range(m):
    a=int(input())
    ab.append(a)
dp = [0]*(n+1)
dp[0] = 1
ana = ab.pop(0)

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