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

A = []
for i in range(m):
    A.append(int(input()))
    
dp = [0 for i in range(n + 1)]
dp[0] = 1

count = 0
for i in range(n+1):
    if  i !=  A[count]:
        if i >= 2:
            dp[i] += (dp[i-2] + dp[i-1]) % (10 ** 9 + 7)
        elif i == 1:
            dp[i] += dp[i-1] % (10 ** 9 + 7)
    else:
        if count < m-1:
            count += 1
            
print(dp[-1] % (10 ** 9 + 7))