#include<stdio.h>
int main(){
	int a[101],i,j,total,l,temp;
	int n,m;
	while(scanf("%d",&n),n){
		m=1;
		total=0;
		l=1;
		for(i=1;i<=n;i++){
			scanf("%d",&a[i]);
		}
		for(i=n;i>=1;i--){
			for(j=1;j<=i;j++){
				if(a[j]<a[i]){
					temp=a[i];
					a[i]=a[j];
					a[j]=temp;
				}
			}
		}
		for(i=1;i<=n;i++){
			if(l<=n-1){
				total+=a[i];
				l++;
			}
			else
			total+=2;
			if(a[i]<=1)
			m=0;
			if(m==0)
			break;
		}
		if(m==0)
		printf("-1\n");
		else
		printf("%d\n",total);
			}
}