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

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

if a[0] != 1:
    dp[1] = 1
    
for i in range(2,n+1):
    if i not in a:
        dp[i] = dp[i-1] + dp[i-2]
        dp[i] %= 1000000007
        
print(dp[n])