n,p,i,a[50];
main(){
	for(;~scanf("%d", &n),n;) {
		for(i=0;i<n;i++)scanf("%d",&a[i]);p=0;
		for(i=1;i<n;i++){
			if(a[i-1]+1!=a[i]) {
				if(i-p-1)printf("%d-%d ",a[p],a[i-1]);
				else printf("%d ",a[p]);
				p=i;
			}
		}
		if(n-p-1)printf("%d-%d\n",a[p],a[n-1]);
		else printf("%d\n",a[p]);
	}
	exit(0);
}