#include <iostream>

 #include <cstdio>

 #include <cstdlib>

 #include <cmath>

 #include <algorithm>

 #include <cstring>

 #include <vector>

 #include <string>

 #include <queue>

 #include <map>

 #include <set>

 #define FRER() freopen("in.txt", "r", stdin);

 #define INF 0x3f3f3f3f

 using namespace std;

 const int maxn =  + ;

 vector<int> stand[maxn << ];

 int brand[maxn], N, K;

 void init() {

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

         stand[i].clear();

     memset(brand, , sizeof(brand));

 }

 int solve() {

     int st = , ed = , ans = INF, k = , now = ;

     while(ed < (N << )) {

         for(int i = ; i < stand[ed].size(); ++i) {

             ++now;

             if(brand[stand[ed][i]] == )

                 ++k;

             ++brand[stand[ed][i]];

         }

         ++ed;

         while(k == K && st < ed) {

             ans = min(ans, now);

             for(int i = ; i < stand[st].size(); ++i) {

                 --now;

                 --brand[stand[st][i]];

                 if(brand[stand[st][i]] == )

                     --k;

             }

             ++st;

         }

     }

     return ans == INF ? - : ans;

 }

 int main()

 {

     //FRER()

     while(~scanf("%d %d", &N, &K)) {

         init();

         int n, num;

         for(int i = ; i < N; ++i) {

             scanf("%d", &n);

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

                 scanf("%d", &num);

                 stand[i].push_back(num);

                 stand[i + N].push_back(num);

             }

         }

         printf("%d\n", solve());

     }

     return ;

 }