n, m = map(int, input().split())
aL = [int(input()) for _ in range(m)]
mod = 10**9+7
cant = 0
dp = [0]*(n+1)
dp[0] = 1
dp[1] = 0 if aL[0] == 1 else 1
for i in range(n-1):
    if i+2 in aL:
        if dp[i+1] > 0:
            dp[i+2] = 0
        else:
            cant = 1
            break
    else:
        dp[i+2] += (dp[i] + dp[i+1]) % mod
if cant == 1:
    print(0)
else:
    print(dp[n])