'use strict';

function isRectangle(elements) {
    let minX=10000, maxX=-10000, minY=10000, maxY=-10000;
    for(let i=0;i<elements.length;i++) {
        if (elements[i].x < minX) {
            minX = elements[i].x;
        }
        if (elements[i].x > maxX) {
            maxX = elements[i].x;
        }
        if (elements[i].y < minY) {
            minY = elements[i].y;
        }
        if (elements[i].y > maxY) {
            maxY = elements[i].y;
        }
    }
    for(let i=0;i<elements.length;i++) {
        if (elements[i].x != maxX && elements[i].x != minX && elements[i].y != minY && elements[i].y != maxY) {
            return false;
        }
    }
    return true;
}

function processData(input) {
    //Enter your code here
    let lines = input.split("\n");
    let queries = parseInt(lines[0]);
    let lineNo = 1;
    for(let i=0;i<queries;i++) {
        let count = parseInt(lines[lineNo]);
        let elements = [];
        lineNo++;
        for (let j = 0; j < count; j++) {
            let coords = lines[lineNo].split(" ");
            elements.push({x: parseInt(coords[0]), y: parseInt(coords[1])});
            lineNo++;
        }
        console.log(isRectangle(elements)?"YES":"NO");
    }
} 

process.stdin.resume();
process.stdin.setEncoding("ascii");
let _input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});