public class Ura{
	public int ura;
	public int min;
	
	public Ura(){
		this.ura = 0;
		this.min = 0;
	}
	
	public Ura(int u, int m){
		this.ura = 0;
		this.min = 0;
		if (u >= 0 && u <= 23)
			this.ura = u;
		if (m >= 0 && m <= 59)
			this.min = m;
	}
	
	public void izpis(){
		if(ura<10)
			System.out.print("0"+ura+":");
		else
			System.out.print(ura+":");
		if(min<10)
			System.out.print("0"+min);
		else
			System.out.print(min);
		System.out.println();
	}
	
	public void povecaj(){
		min = (min+1)%60;
		if (min == 0)
			ura = (ura+1)%24;
	}
	
	public static void main(String[]args){
		Ura u = new Ura();
		u.izpis();
		u.povecaj();
		u.izpis();  // izpiše 00:01
		Ura v = new Ura(23,59);
		v.izpis();  // izpiše 23:59
		v.povecaj();
		v.izpis();  // izpiše 00:00 
	}
}