n, m = map(int, input().split())

holes = [ int(input()) for _ in range(m) ]


DIV = 10**9+7

dp = [0 for _ in range(n+1)]
dp[0] = 1
if 1 not in holes:
    dp[1] = 1

for i in range(2, n+1):
    if i not in holes:
        dp[i] = (dp[i-1] + dp[i-2]) % DIV

print(dp[n])