package main

import (
	"bufio"
	"fmt"
	"os"
)

type Edge struct {
	u, v int
}

func main() {
	in := bufio.NewReader(os.Stdin)
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	var n int
	if _, err := fmt.Fscan(in, &n); err != nil {
		return
	}

	a := make([]int, n+1)
	core := make([]int, 0, n)
	leaf := make([]int, 0, n)

	for i := 1; i <= n; i++ {
		fmt.Fscan(in, &a[i])
		if a[i] > 1 {
			core = append(core, i)
		} else {
			leaf = append(leaf, i)
		}
	}

	if n == 1 {
		fmt.Fprintln(out, "YES 0")
		fmt.Fprintln(out, 0)
		return
	}

	if n == 2 {
		fmt.Fprintln(out, "YES 1")
		fmt.Fprintln(out, 1)
		fmt.Fprintln(out, 1, 2)
		return
	}

	if len(core) == 0 {
		fmt.Fprintln(out, "NO")
		return
	}

	rem := make([]int, n+1)
	copy(rem, a)

	edges := make([]Edge, 0, n-1)

	for i := 0; i+1 < len(core); i++ {
		u, v := core[i], core[i+1]
		rem[u]--
		rem[v]--
		if rem[u] < 0 || rem[v] < 0 {
			fmt.Fprintln(out, "NO")
			return
		}
		edges = append(edges, Edge{u, v})
	}

	diameter := len(core) - 1
	if len(leaf) == 1 {
		diameter++
	} else if len(leaf) >= 2 {
		diameter += 2
	}

	if len(core) == 1 {
		c := core[0]
		if rem[c] < len(leaf) {
			fmt.Fprintln(out, "NO")
			return
		}
		for _, v := range leaf {
			edges = append(edges, Edge{c, v})
			rem[c]--
		}
	} else {
		idx := 0

		if idx < len(leaf) {
			u := core[0]
			if rem[u] == 0 {
				fmt.Fprintln(out, "NO")
				return
			}
			edges = append(edges, Edge{u, leaf[idx]})
			rem[u]--
			idx++
		}

		if idx < len(leaf) {
			u := core[len(core)-1]
			if rem[u] == 0 {
				fmt.Fprintln(out, "NO")
				return
			}
			edges = append(edges, Edge{u, leaf[idx]})
			rem[u]--
			idx++
		}

		p := 0
		for idx < len(leaf) {
			for p < len(core) && rem[core[p]] == 0 {
				p++
			}
			if p == len(core) {
				fmt.Fprintln(out, "NO")
				return
			}
			u := core[p]
			edges = append(edges, Edge{u, leaf[idx]})
			rem[u]--
			idx++
		}
	}

	if len(edges) != n-1 {
		fmt.Fprintln(out, "NO")
		return
	}

	fmt.Fprintf(out, "YES %d\n", diameter)
	fmt.Fprintln(out, len(edges))
	for _, e := range edges {
		fmt.Fprintln(out, e.u, e.v)
	}
}