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