/* package whatever; // don't place package name! */

import java.util.*;
class Main{
	static class Node{
		int data;
		Node next;
		Node(int data){
			this.data = data;
		}
	}
	static Node buildlist(int[] vals){
		Node head = null,tail=null;
		for(int val : vals){
			Node newNode = new Node(val);
			if(head == null){
				head = newNode;
				tail = newNode;
			}else{
				tail.next = newNode;
				tail = newNode;
			}
		}
		return head;
	}
	static Node reverse(Node head){
		Node curr=head.next; Node prev = null;
		while(curr!=null){
			Node next = curr.next;
			curr.next = prev;
			prev = curr;
			curr = next;
		}
		return head;
	}
	static boolean check(Node head,Node head1){
		Node curr = head.next,curr1 = head1.next;
		while(curr.next!=null&&curr1.next!=null){
			if(curr != curr1) return false;
			curr = curr.next;
			curr1 = curr1.next;
		}
		return true;
	}
	public static void main(String[]args){
		Scanner cs = new Scanner(System.in);
		int n = cs.nextInt();
		int[] arr = new int[n];
		for(int i=0; i<n; i++){
			arr[i] = cs.nextInt();
		}
		Node head = buildlist(arr);
		Node head1 = reverse(head);
		
		System.out.println(check(head,head1)? "yes" : "no");
	}
}