#include<iostream>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstdio>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define it ::iterator
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double ESP=1e-10;
using namespace std;
int main(){
  int n;
  while(cin>>n,n){
    vector<int>in(n);
    rep(i,n)cin>>in[i];
    bool h1=false;
    rep(i,n){
      if(h1)cout<<' ';
      h1=true;
      cout<<in[i];
      bool h=false;
      if(i+1<n)while(in[i]+1==in[i+1]){i++;h=true;if(i==n-1)break;}
      if(h)cout<<'-'<<in[i];
    }
    cout<<endl;
  }
}