import java.util.Scanner;

public class prog{

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn = new Scanner(System.in);
		int N = scn.nextInt();
		int[] arr = new int[N];
		for (int i = 0; i < N; i++) {
			arr[i] = scn.nextInt();
		}
		for (int i = 0; i < N - 1; i++) {
			int a = arr[i];
			int b = arr[i + 1];
			if (b - a > 1) {
				System.out.println(a + 1 + "-" + (b - 1));
			}
			if (i == N - 2) {
				if (b != 100) {
					System.out.println(b + 1 + "-" + 100);
				}
			}
		}

	}

}