#include<cstdio>

#include<cctype>

#include<algorithm>

using namespace std;

const int maxn=;

int f1[maxn*],f2[maxn*],mp[maxn][maxn],n,h,delta;

int read()

{

    char c;int s=;

    while(!isdigit(c=getchar()));

    do{s=s*+c-'';}while(isdigit(c=getchar()));

    return s;

}

int main()

{

    n=read(),h=read(),delta=read();

    for(int i=;i<=n;i++)

     {

         int m,k;

         m=read();

         for(int j=;j<=m;j++)k=read(),mp[i][k]++;

     }

    for(int i=h;i>;i--)

     {

         for(int j=;j<=n;j++)

          {

              f1[j]=max(f1[j],f2[i+delta])+mp[j][i];

              f2[i]=max(f2[i],f1[j]);

          }

     }

    printf("%d",f2[]);

    return ;

}