import java.util.Scanner;

public class Speed_Calvin {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNextLine()) {
			String t = in.nextLine();
			Scanner in2 = new Scanner(t);
			if (t.equals("0 0 0")) {
				break;
			}
			double d = in2.nextInt();
			double s1 = in2.nextInt();
			double s2 = in2.nextInt();
			in2.close();
			double ss1 = s1/3600.0;
			double ss2 = s2/3600.0;
			double t1 = d/ss1;
			double t2 = d/ss2;
			double d1 = t1 - t2;
			int h = (int) (d1/3600);
			d1 = d1 - 3600*h;
			int m = (int) (d1 / 60);
			d1 = d1 - 60 * m;
			int s = (int) Math.round(d1);
			String ms = String.valueOf(m);
			String ss = String.valueOf(s);
			if (m < 10) {
				ms = "0" + ms;
			}
			if (s < 10) {
				ss = "0" + ss;
			}
			System.out.println(h + ":" + ms + ":" + ss);
		}
		in.close();
	}
}