package main

import (
	"fmt"
)

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

	var minX, minY int64 = 1000000, 1000000
	var maxX, maxY int64 = -1, -1
	var totalArea int64 = 0

	for i := 0; i < n; i++ {
		var x1, y1, x2, y2 int64
		fmt.Scan(&x1, &y1, &x2, &y2)
		if x1 < minX {
			minX = x1
		}
		if y1 < minY {
			minY = y1
		}
		if x2 > maxX {
			maxX = x2
		}
		if y2 > maxY {
			maxY = y2
		}
		totalArea += (x2 - x1) * (y2 - y1)
	}

	width := maxX - minX
	height := maxY - minY

	if width > 0 && width == height && totalArea == width*height {
		fmt.Println("YES")
	} else {
		fmt.Println("NO")
	}
}