N, M = map(int, input().split(' '))
dp = [0 for _ in range(N + 1)]
for _ in range(M):
    i = int(input())
    dp[i] = -float('inf')

dp[0] = 1
for i in range(N+1):
    if 0 <= i-1 < N and dp[i-1] != -float('inf'):
        dp[i] += dp[i-1]

    if 0 <= i-2 < N and dp[i-2] != -float('inf'):
        dp[i] += dp[i-2]

print(dp[N] % 1000000007 )