N,M = map(int, input().split())
l = [int(input()) for i in range(M)]

dp = [0] * (N+1)
dp[0] = 1
dp[1] = 1
mod = 1000000007

if 1 in l:
    dp[1] = 0

for i in range(2,N+1):
    if i in l:
        dp[i] = 0
    else:
        dp[i] = dp[i-1] + dp[i-2]
    dp[i] %= mod
print(dp[N])
