N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
D = 1000000007
dp = [1]*(N+1)
for i in a:
    dp[i] = 0
for i in range(2, len(dp)):
    if i in a:
        continue
    dp[i] = dp[i-1] + dp[i-2]
print(dp[-1]%D)