#include<iostream>
using namespace std;
int v[10002],n;
int main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
        {
            cin>>v[i];
        }
    for(int i=1;i<=n;i+=2)
         if(v[i+1]-v[i]!=0) cout<<v[i]+1<<"-"<<v[i+1]-1<<endl;
}