mod = 1000000007
def add(a, b):
    return (a + b) % mod

N, M = map(int, input().split())
Broken_set = set([])
for _ in range(M):
    Broken_set.add(int(input()))

if 1 in Broken_set:    
    dp = [0]*(N+1)
    dp[0] = 1
    dp[1] = 0
    for i in range(3, N+1):
        if i in Broken_set:
            dp[i] = 0
        else:
            dp[i] = add(dp[i-1], dp[i-2])

else:
    dp = [0]*(N+1)
    dp[0] = 1
    dp[1] = 1
    for i in range(2, N+1):
        if i in Broken_set:
            dp[i] = 0
        else:
            dp[i] = add(dp[i-1], dp[i-2])

print(dp[N])