class Frekvens<T extends Comparable<T>> {
    class Node {
	Node neste = null;
	T data;
	int antall = 1;

	Node(T n) {
	    data = n;
	}
    }

    Node forste = null, siste = null;

    T flest;
    int flestAntall;

    T hentFlest() { return flest; }
    int hentAntall() { return flestAntall; }

    void add(T x) {
	if (forste == null) {
	    forste = siste = new Node(x);
	} else {
	    siste.neste = siste = new Node(x);
	}
    }

    void komprimer() {
	Node p1 = forste, p2 = forste.neste;

	while (p2 != null) {
	    if (p1.data.compareTo(p2.data) == 0) {
		p1.antall++;  p1.neste = p2.neste;
	    } else {
		p1 = p2;  
	    }
	    p2 = p2.neste;
	}
    }

    void finnFlest() {
	flest = null;
	flestAntall = 0;

	Node p = forste;
	while (p != null) {
	    if (p.antall > flestAntall) {
		flest = p.data;  flestAntall = p.antall;
	    }
	    p = p.neste;
	}
    }

    void visData() {
	Node p = forste;

	while (p != null) {
	    System.out.print(p.data + "(" + p.antall + ")  ");
	    p = p.neste;
	}
	System.out.println();
    }
}

class Dato implements Comparable<Dato> {
    int aa, m, d;

    Dato(int aa, int m, int d) {
	this.aa = aa;  this.m = m;  this.d = d;
    }

    @Override
    public int compareTo(Dato x) {
	if (aa != x.aa) return aa - x.aa;
	if (m != x.m) return m - x.m;
	return d - x.d;
    }

    @Override
    public String toString() {
	return aa + "-" + m + "-" + d;
    }
}

class BrukFrekvens {
    public static void main(String[] arg) {
	Frekvens<Dato> mineData = new Frekvens<>();
	mineData.add(new Dato(2000,  1,  1));
	mineData.add(new Dato(2020,  5, 10));
	mineData.add(new Dato(2020,  5, 10));
	mineData.add(new Dato(2020,  5, 17));
	mineData.add(new Dato(2020,  7, 17));

	mineData.komprimer();
	mineData.finnFlest();
	System.out.println("Den vanligste datoen er " + 
            mineData.hentFlest() + " (" + 
            mineData.hentAntall() + " forekomster).");
    }
}

//	System.out.print("Data er ");  mineData.visData();