N,M=map(int,input().split())
a = [int(input()) for _ in range(M)]
dp = [0]*(N+1)
j = 0
dp[0] = 1
mod = 10**9+7
for i in range(1, N+1):
    if i == a[j]:
        j += 1
        j = min(M-1, j)
    elif i == 1:
        dp[i] = 1
    else:
        dp[i] = (dp[i-1]+dp[i-2]) % mod
print(dp[N])