n, m = map(int, input().split())
mod = 10e9+7
dp = [0]*(n+1)
dp[0] = 1
isPass = [1]*(n+1)
for _ in range(m):
    a = int(input())
    isPass[a] = 0
for i in range(n):
    for j in range(i+1, min(n, i+2)+1):
        if isPass[j]:
            dp[j] += dp[i]
            dp[j] %= mod
print(dp[n])