#include <algorithm>
#include <utility>
#include <stdio.h>
#include <vector>

#define fi first
#define se second
using namespace std;

typedef vector<pair<int,int> > vii;
typedef pair<int, int> pii;
int sample[10000001];


int main(void){
	int n,k;
	while(scanf("%d %d", &n, &k) == 2){
		vii a[n];
		vii prefs[2*n+10];
		for(int i = 0; i < n; i++){

			int samp_in_v;
			scanf("%d", &samp_in_v);

			for(int j = 0; j < samp_in_v; j++)
				scanf("%d", &sample[j]);

			sort(sample, sample + samp_in_v);

			int j = 0;
			int kolik = 1;
			while(j < samp_in_v-1){
				if(sample[j] != sample[j+1]){
					a[i].push_back({sample[j], kolik});
					kolik = 1;
				}
				else
					kolik++;
				j++;
			}
			a[i].push_back({sample[samp_in_v-1],kolik});
			/*printf("vrchol %d\n", i);
			for(int k = 0; k < samp_in_v; k++){
				printf("%d ", sample[k]);
			}
			printf("\n");
			for(int vzorek = 0; vzorek < a[i].size(); vzorek++){
				printf("barva %d kolik %d\n", a[i][vzorek].fi, a[i][vzorek].se);
			}
			printf("\n");*/
			
		}
		for(int end = 1; end <= 2*n; end++){
			int psi = 0;
			int vi = 0;
			while(psi < prefs[end-1].size() || vi < a[(end-1)%n].size()){
				if(psi >= prefs[end-1].size()){
					prefs[end].push_back(a[(end-1)%n][vi]);
					vi++;
					continue;
				}
				if(vi >= a[(end-1)%n].size()){
					prefs[end].push_back(prefs[end-1][psi]);
					psi++;
					continue;
				}
				pii pend = prefs[end-1][psi];
				pii aend = a[(end-1)%n][vi];

				if(pend.fi == aend.fi){
					prefs[end].push_back({pend.fi, pend.se+aend.se});
					psi++;
					vi++;
				}
				else if(pend.fi < aend.fi){
					prefs[end].push_back(pend);
					psi++;
				}
				else{
					prefs[end].push_back(aend);
					vi++;
				}
			}
			/*printf("vrchol %d\n", end);
			for(int vzorek = 0; vzorek < prefs[end].size(); vzorek++){
				printf("barva %d kolik %d\n", prefs[end][vzorek].fi, prefs[end][vzorek].se);
			}
			printf("\n");*/
		}
		int mn = 99999999;
		for(int end = 1; end <= 2*n; end++){
			if(prefs[end].size() < k) continue;
			int l = 0;
			int r = end;
//			printf("zacinam pro %d\n", end);
			int tmpmin = 99999999;
			while(l!=r-1){
				int sum = 0;
				bool rnastaveno = false;
				//printf("%d %d\n",l,r);
				int mid = (l+r)/2;
				int midi = 0;
				for(int bar = 0; bar < prefs[end].size(); bar++){
					pii pend = prefs[end][bar];
					pii mend = prefs[mid][midi];
					if(prefs[end][bar].fi == prefs[mid][midi].fi){
						midi++;
						if(pend.se <= mend.se){
							r = mid;
							rnastaveno = true;
							break;
						}
						else
							sum += pend.se - mend.se;
					}
					else{
						sum += pend.se;
					}
				}
				if(!rnastaveno){
					l = mid;
					tmpmin = min(tmpmin,sum);
				}
			}
			mn = min(mn, tmpmin);
		}
		printf("%d\n", (mn != 99999999) ? mn : -1);
	}
}