#include <iostream>

using namespace std;

int fr[102];

int main ()
{
    int n,x,cop;
    cin>>n;
    for (int i=1; i<=n; i++)
    {
        cin>>x; fr[x]++;
    }
    int j=1;
    while (j<=100)
    {
        cop=j;
        while (fr[cop]==0 && cop<=100) cop++;
        if (cop!=j)
        {
            cout<<j<<"-"<<cop-1<<"\n";
            j=cop;
        }
        else j++;
    }

}