#include <stdio.h>

int main(){
    int n;
    scanf("%d",&n);
    int a[n];
    for (int i=0;i<n;i++){
            scanf("%d",&a[i]);
            }
    for (int i=0;i<n-1;++i){

        if (a[i]==a[i+1]-1){
           printf("%d-",a[i]);
           while (a[i]==a[i+1]-1)
                 ++i;
           if(i!=n-1)
           printf("%d,",a[i]);}
        else
            printf("%d,",a[i]);
        }
    printf("%d\n",a[n-1]);
    }