#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef long double ld;
typedef tuple<int, int> duo;

#define TT template<typename T>
#define ET(T) typename T::value_type
TT inline T sq(T x){return x*x;}
TT inline T In(){T x;cin>>x;return x;}
TT inline int ubnd(T&v,ET(T) x){return upper_bound(begin(v),end(v),x)-begin(v);}
TT inline int lbnd(T&v,ET(T) x){return lower_bound(begin(v),end(v),x)-begin(v);}
TT inline void sort(T&v){sort(begin(v),end(v));}
TT inline void revs(T&v){reverse(begin(v),end(v));}
TT inline void uniq(T&v){sort(v);v.erase(unique(begin(v),end(v)),end(v));}
TT inline void inpt(T&v,int n,function<ET(T)()>f=In<ET(T)>){for(v.reserve(n);n--;v.emplace_back(f()));}
TT inline void show(T&v,string d=" ",string e="\n"){int i=0;for(auto&x:v)i++&&(cout<<d),cout<<x;cout<<e;}
#undef TT
#undef ET

inline void fast_io(){ios::sync_with_stdio(0); cin.tie(0);}
inline int in(){int x;scanf("%d",&x);return x;}
inline string instr(){string x;cin>>x;return x;}
inline ll pow_mod(ll a, ll k, ll m){ll r=1;for(;k>0;a=a*a%m,k>>=1)if(k&1)r=r*a%m;return r;}
inline ll mod_inv(ll a, ll p){return pow_mod(a,p-2,p);}

const int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
const int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
const int Mod = 1000000000;

int main()
{
  int n;
  while (n = in()){
    queue<int> q;
    int flag = 0;
    for (int i = 0; i < n; i++) q.push(in());
    while (!q.empty()){
      int x = q.front();
      q.pop();
      int a = x;
      while (!q.empty() && a + 1 == q.front()){
        a++;
        q.pop();
      }
      if (flag++) printf(" ");
      if (x == a) printf("%d", x);
      else printf("%d-%d", x, a);
    }
    puts("");
  }
  return (0);
}

// priority_queue queue deque front top push pop map set stringstream max_element min_element insert count find get tie make_tuple