n, m = map(int,input().split())
a = [int(input()) for i in range(m)]
dp = [float("inf")] * (n+1)
dp[0] = 1
dp[1] = 1
for i in a:
    dp[i] = 0
for i in range(2, n+1):
    dp[i] = min(dp[i], (dp[i-1] + dp[i-2])%10**9+7)
print(dp[n])
