N, M = map(int, input().split())
a = [0] * M
for i in range(M):
    a[i] = int(input())


dp = [0] * (N+1)

for i in range(N+1):
    if i == 0:
        dp[i] = 1
    elif i == 1:
        if i in a:
            dp[i] = 0
        elif i not in a:
            dp[i] = 1
    else:
        if i in a:
            dp[i] = 0
        else:
            dp[i] = dp[i-1] + dp[i-2]
            dp[i] = dp[i] % 1000000007

ans = dp[N]
print(ans)