#include <bis/stdc++.h>

using namespace std;

int main()
{

freopen("test.in" , "r" , stdin);
freopen("test.out" , "w" , stdout);

scanf("%d" , &n);
scanf("%d" , &k);

for (i = 1 ; i <= n ; ++i)
{
    scanf("%d" , &d[i % 2][0]);
    for (j = 1 ; j <= d[i % 2][0] ; ++j)
    scanf("%d" , &d[i % 2][j]);

    if (i == 1) continue;

    j = 1;
    while (j <= d[i % 2][0] && j <= d[1 - i % 2][0] && d[i % 2][j] == d[1 - i % 2][j])
    j++;

    if (j == min(d[i % 2][0] , d[1 - i % 2][0]) + 1)
    {
        if (d[i % 2][0] < d[1 - i % 2][0])
        {
            printf("-1\n");
            return 0;
        }
        else continue;
    }

    moves.push_back(make_pair(d[1 - i % 2][j] , d[i % 2][j]));
    used[d[i % 2][j]] = 1;
}

for (i = 1 ; i <= k ; ++i)
if (!used[i]) break;

if (i == k + 1)
{
    printf("-1\n");
    return 0;
}

for (j = 1 ; j <= c - k + 1 ; ++j)
p[j] = i++;

i = 1;
for (j = c - k + 2 ; j <= c ; ++j)
p[j] = i++;

return 0;
}