n,p,i,a[51];
main(){
	for(;~scanf("%d", &n),n;) {
		for(a[n]=p=i=0;i<n;i++)scanf("%d",a+i);
		for(i=1;i<=n;i){
			if(a[i-1]+1!=a[i]) {
				if(i-p-1)printf(n-i?"%d-%d ":"%d-%d\n",a[p],a[i-1]);
				else printf(n-i?"%d ":"%d\n",a[p]);
				p=i++;
			}
		}
	}
	exit(0);
}