import java.io.*;
import java.util.*;

public class Balance_nomura{
	static int eatSubtree(int[] a,int sum,int pos){
		if(sum==0) return pos;
		if(pos<0 || sum<0 || pos==a.length) return -1;
		return eatSubtree(a,sum-a[pos],eatSubtree(a,sum-a[pos],pos+1));
	}
	
	static boolean solve(int[] a){
		if(a.length%2==0) return false;
		
		int sum=a[0];
		for(int i=1;i<=a.length/2;i++){
			sum+=a[i];
			if(eatSubtree(a,sum,0)==a.length) return true;
		}
		
		return false;
	}
	
	public static void main(String[] args) throws Exception{
		BufferedReader br=new BufferedReader(new FileReader("balance.in"));
		
		while(true){
			StringTokenizer st=new StringTokenizer(br.readLine());
			
			int n=Integer.parseInt(st.nextToken());
			if(n==0) break;
			
			int[] a=new int[n];
			for(int i=0;i<n;i++) a[i]=Integer.parseInt(st.nextToken());
			
			System.out.println(solve(a) ? "yes" : "no");
		}
	}
}