#include<bits/stdc++.h>

#define FOR(i,a,b) for(auto i=a; i!=b+1-2*(a>b); i+=1-2*(a>b))
#define REP(i,a,b) for(auto i=a-(a>b); i!=b-(a>b); i+=1-2*(a>b))
#define ALL(v) v.begin(),v.end()
#define what_is(x) cout<<#x<<" is "<<x<<endl;
#define min3(a,b,c) min(min(a,b),c)
#define max3(a,b,c) max(max(a,b),c)
#define SIZE 1910
#define MAXN 10000000007
#define PI 3.141592653589793
#define open_read1 freopen("C:\\Users\\Hepic\\Desktop\\a.txt","r",stdin)
#define open_read freopen("rblock.in","r",stdin)
#define open_write freopen("rblock.out","w",stdout)

using namespace std;


typedef long long LL;
typedef pair<int,int> PII;


LL B,F,I;
LL people_per_build,Tfloor,max_val,max_people;
LL num_of_people[SIZE][SIZE],dp_max[SIZE][SIZE];


int main()
{
    //open_read1;
    scanf("%lld%lld%lld",&B,&F,&I);


    FOR(b,1,B)
    {
        scanf("%lld",&people_per_build);

        FOR(t,1,people_per_build)
        {
            scanf("%lld",&Tfloor);
            ++num_of_people[Tfloor][b];
        }
    }



    FOR(f,F,1)
    {
        max_val=0;
        if(f+I<=F)
            FOR(i,1,B)
                max_val = max(max_val, dp_max[f+I][i]);


        FOR(b,1,B)
        {
            if(f+1<=F)
                dp_max[f][b] = num_of_people[f][b] + max(max_val, dp_max[f+1][b]);

            else
                 dp_max[f][b] = num_of_people[f][b] + max_val;
        }
    }



    FOR(b,1,B)
        max_people = max(max_people, dp_max[1][b]);

    printf("%lld\n",max_people);


    return 0;
}