import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;


public class game {

	public static void main(String[] args) throws FileNotFoundException {
		Scanner sc = new Scanner(new File("game.in"));
		for (;;) {
			int n = sc.nextInt();
			if (n==0) break;
			
			long[] a = new long[n];
			for (int i=0; i<n; i++) a[i] = sc.nextInt();
			
			System.out.println(solve(a, n-1));
		}
		
	}
	
	static long solve(long[] a, int pos) {
		if (pos==0) return a[0];
		for (int i=0; i<pos; i++) a[i]+=a[pos];
		return a[pos]+solve(a, pos-1);
	}

}