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

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

for i in range(1, N+1):
    if i in a:
        dp[i] = 0
        if dp[i-1] == 0:
            ans = 0
            break
    else:
        try:
            dp[i] = dp[i-1] + dp[i-2]
        except:
            dp[i] = dp[i-1]
else:
    ans = dp[-1] % 1000000007

print(ans)
