N,M = map(int, input().split())

MOD = 10**9 + 7

a = [int(input()) for _ in range(M)]

dp = [0] * (N+1)
dp[0] = 1
dp[1] = 1
dp[2] = 2

for i in range(1,N+1):
    if (i in a):
        dp[i] = 0
        continue
    dp[i] = (dp[i-1]) + (dp[i-2])
print(dp[i]%MOD)
