(DP) bzoj 1978

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<algorithm>
#include<cstdlib>
using namespace std;
int n,l;
int ans,dp[50005],pre[50005];
int main()
{
    int x;
    scanf("%d%d",&n,&l);
    for(int i=1;i<=n;i++)
    {
        scanf("%d",&x);
        for(int j=1;j<=sqrt(x);j++)
        {
            if(x%j==0)
            {
                if(j>=l)
                    dp[i]=max(dp[i],dp[pre[j]]+1),pre[j]=i;
                int k=x/j;
                if(k>=l)
                    dp[i]=max(dp[i],dp[pre[k]]+1),pre[k]=i;
            }
        }
        ans=max(ans,dp[i]);
    }
    printf("%d\n",ans);
    return 0;
}