n, m = map(int, input().split())
a = int(input()) for _ in range(m)
 
dp = [0] * 10000
dp[0] = 1
if 1 not in a:
    dp[1] = 1
 
for i in range(2, n + 1):
    if  (i - 1) not in a:
        dp[i] = dp[i] + dp[i - 1]
    if (i - 2) not in a:
        dp[i] = dp[i - 2] + dp[i] 
    
    dp[i] %= 1000000007
    
print(dp[n])