/*** https://mindcoding.ro/pb/gaps ***/

#include <iostream>

using namespace std;
int main()
{
    int N;
    cin >> N;

    if (N < 1 || N > 100) return 0;

    int* numbers = new int[N];
    for (int i = 0; i < N; i++) {
        cin >> numbers[i];
    }

    int nr = 1, arrayCounter = 0;
    bool isGap = false;

    for (int i = 1; i <= 100; i++) {
        if (i == numbers[arrayCounter]) {
            if (isGap) {
                cout << nr << "-" << i-1 << endl;
            }

            arrayCounter++;
            isGap = false;
            continue;
        }

        if (!isGap) {
            isGap = true;
            nr = i;
        }
    }

    if (isGap) {
        cout << nr << "-" << 100 << endl;
    }

    return 0;
}