#include <stdio.h>
#include <stdlib.h>

int c_zero, sum_sampl, *sampl;
void putsamp(int k) {
    if (sampl[k] == 0)
        c_zero--;
    sum_sampl++;
    sampl[k]++;
}

void delsamp(int k) {
    sum_sampl--;
    sampl[k]--;
    if (sampl[k] == 0)
        c_zero++;
}

int main(){
    int i, j, n, k, left, right, ans, c_semp;
    int ** array;

    while(1){
        if (scanf("%i %i", &n, &k) != 2) break;

        array = malloc((sizeof(*array)*n));
        for (i = 0; i < n; i++){
            scanf("%i", &c_semp);
            *(array + i) = malloc(sizeof(int)*(c_semp+1));
            **(array + i) = c_semp;
            for (j = 1; j <= c_semp; j++){
                scanf("%i", (*(array + i) + j));
            }
        }
        sampl = malloc (sizeof(int)*(k + 1));
        for (i = 0; i < k + 1; i++) sampl[i] = 0;

        c_zero = k; sum_sampl = 0;
        left = 0; right = 0;
        ans = 100000000;
        for (i = 1; i <= **(array); i++)
            putsamp(*(*(array) + i));
        while(1){
            if (c_zero == 0) {
                if (sum_sampl < ans)
                    ans = sum_sampl;
                for (i = 1; i <= **(array + left); i++)
                    delsamp(*(*(array + left) + i));
                left++;
                if (left == n) break;
            } else {
                right = (right + 1) % n;
                if ((right == 0) && (ans == 100000000)) break;
                for (i = 1; i <= **(array + right); i++)
                    putsamp(*(*(array + right) + i));
            }

        }
        if (ans == 100000000)
            printf("-1\n");
        else
            printf("%i\n", ans);
    }

    return 0;
}