import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

class Pair {
    private final Integer a;
    private final Integer b;

    Pair(Integer a, Integer b) {
        this.a = a;
        this.b = b;
    }

    public Integer getA() {
        return a;
    }

    public Integer getB() {
        return b;
    }

    @Override
    public String toString() {
        return "Pair{" +
                "a=" + a +
                ", b=" + b +
                '}';
    }
}

public class Application {

    private static Pair findMinimumRange(List<List<Integer>> lists) {
        int m = lists.size();
        List<Pair> merged = new ArrayList<>();
        for (int i = 0; i < lists.size(); i++) {
             List<Integer> list = lists.get(i);
            for (Integer integer : list) {
                merged.add(new Pair(integer, i));
            }
        }
        merged.sort(Comparator.comparingInt(Pair::getA));

        ArrayList<Integer> counter = new ArrayList<>();
        for (int i = 0; i < lists.size(); ++i) {
            counter.add(0);
        }
        int current_classes = 0;
        int l = 0;
        int r = 0;

        int min_value = merged.get(merged.size()-1).getA() - merged.get(0).getA();
        int min_l = 0;
        int min_r = merged.size() - 1;

        while (true) {
            if (current_classes < m) {
                if (r == merged.size()) {
                    break;
                }
                r++;
                int cat = merged.get(r-1).getB();
                if (counter.get(cat) == 0) {
                    current_classes += 1;
                }
                counter.set(cat, counter.get(cat) + 1);
            } else {
                int cur_value = merged.get(r-1).getA() - merged.get(l).getA();
                if (cur_value < min_value) {
                    min_value = cur_value;
                    min_l = l;
                    min_r = r;
                }
                int cat = merged.get(l).getB();
                if (counter.get(cat) == 1) {
                    current_classes -= 1;
                }
                counter.set(cat, counter.get(cat) - 1);
                l++;
            }
        }
        return new Pair(merged.get(min_l).getA(), merged.get(min_r-1).getA());
    }

    public static void main(String[] args) {
        List<List<Integer>> lists = Arrays.asList(Arrays.asList(4, 10, 15, 24, 26),
                Arrays.asList(0, 9, 12, 20),
                Arrays.asList(5, 18, 22, 30));
        System.out.println(findMinimumRange(lists));
    }
}