Problem: Graph constructive problems are back! This time the graph you are asked to build should match the following properties.

The graph is connected if and only if there exists a path between every pair of vertices.

The diameter (aka "longest shortest path") of a connected undirected graph is the maximum number of edges in the shortest path between any pair of its vertices.

The degree of a vertex is the number of edges incident to it.

Given a sequence of n integers a_1, a_2, ..., a_n construct a connected undirected graph of n vertices such that:

  * the graph contains no self-loops and no multiple edges; 
  * the degree d_i of the i-th vertex doesn't exceed a_i (i.e. d_i ≤ a_i); 
  * the diameter of the graph is maximum possible. 



Output the resulting graph or report that no solution exists.

Input

The first line contains a single integer n (3 ≤ n ≤ 500) — the number of vertices in the graph.

The second line contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ n - 1) — the upper limits to vertex degrees.

Output

Print "NO" if no graph can be constructed under the given conditions.

Otherwise print "YES" and the diameter of the resulting graph in the first line.

The second line should contain a single integer m — the number of edges in the resulting graph.

The i-th of the next m lines should contain two integers v_i, u_i (1 ≤ v_i, u_i ≤ n, v_i ≠ u_i) — the description of the i-th edge. The graph should contain no multiple edges — for each pair (x, y) you output, you should output no more pairs (x, y) or (y, x).

Examples

Input


3
2 2 2


Output


YES 2
2
1 2
2 3


Input


5
1 4 1 1 1


Output


YES 2
4
1 2
3 2
4 2
5 2


Input


3
1 1 1


Output


NO

Note

Here are the graphs for the first two example cases. Both have diameter of 2.

<image> d_1 = 1 ≤ a_1 = 2

d_2 = 2 ≤ a_2 = 2

d_3 = 1 ≤ a_3 = 2 

<image> d_1 = 1 ≤ a_1 = 1

d_2 = 4 ≤ a_2 = 4

d_3 = 1 ≤ a_3 = 1

d_4 = 1 ≤ a_4 = 1 

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.*;

public class D {

	public static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	public static PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));

	public static void main(String[] args) throws IOException {
		readInput();
		out.close();
	}
	static class Node implements Comparable<Node>{
		int i, v;
		int extra = 0;
		public Node(int a, int b) {
			i=a;
			v=b;
		}
		public int compareTo(Node o) {
			return v - o.v;
		}
	}
	static List<Integer> x = new ArrayList<Integer>(), y = new ArrayList<Integer>();
	static void push(Node a, Node b) {
		x.add(a.i);
		y.add(b.i);
		a.v--;
		b.v--;
		a.extra++;
		b.extra++;
	}
	public static void readInput() throws IOException {
		// br = new BufferedReader(new FileReader(".in"));
		// out = new PrintWriter(new FileWriter(".out"));
		int n=  Integer.parseInt(br.readLine());
		StringTokenizer st = new StringTokenizer(br.readLine());
		Integer[] a = new Integer[n];
		int s = 0;
		for (int i= 0 ; i < n; i++) s += (a[i] = Integer.parseInt(st.nextToken()));
		if (s < n*2-2) {
			out.println("NO");
		}
		else {
			
			List<Node> ones = new ArrayList<Node>(), norm = new ArrayList<Node>();
			for (int i = 0; i < n; i++) {
				if (a[i] == 1) ones.add(new Node(i+1,1));
				else norm.add(new Node(i+1,a[i]));
			}
			// First, link up everything normal. Leave two greatest nodes on the ends.
			// Then, greedily shit to the graph until it works.
			Collections.sort(norm,Collections.reverseOrder());
			Node toadd = norm.remove(0);
			norm.add(toadd);
			for (int i = 0; i < norm.size()-1; i++) {
				push(norm.get(i),norm.get(i+1));
			}
			int ptr = 0;
			for (int i = 0; i < ones.size(); i++) {
				//System.out.println(norm.get(ptr).v + " " );
				if (i == 01) {
					push(norm.get(0),ones.get(i));
				}
				else if (i == 0) {
					push(norm.get(norm.size()-1),ones.get(i));
				}
				else {
					while (norm.get(ptr).v == 0) {ptr++;}
					push(norm.get(ptr),ones.get(i));
				}
			}
			int size = norm.size()-1;
			if (size == 0) {
				size += Integer.min(norm.get(0).extra,2);
			}
			else {
				if (norm.get(0).extra >= 2) size++;
				if (norm.get(norm.size()-1).extra >= 2) size++;
			}
			out.println("YES " + size);
			out.println(n-1);
			for (int i = 0; i < n-1; i++) out.println(x.get(i) + " " + y.get(i));
		}
	}
}