n,m = map(int,input().split())

a = []
for _ in range(m):
    a.append(int(input()))

dp = [0 for _ in range(n+1)]
dp[0] = 1
dp[1] = 1
dp[2] = 2
if m == 0:
    for i in range(2,n+1):
        dp[i] = dp[i-1] + dp[i-2]
    print(dp[n]%(10**9+7))
else:
    c = 0
    for i in range(1,n+1):
        if i == a[c]:
            dp[i] = 0
            if c < m-1:
                c += 1
        else:
            dp[i] = dp[i-1] + dp[i-2]

    print(dp[n]%(10**9+7))
