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