function processData(input) {
    //Enter your code here
    var a1 = input.split("\n");
    var q = a1[0]*1;
    var j = 1;
    for (var qq=0;qq<q;qq++) {
        var n = a1[j]*1;j++;
        var a = [];
        var x1, y1, x2, y2;        
        for (var i=0;i<n;i++) {
            a[i] = a1[j].split(" ").map(Number);j++;
        }

        x1 = a[0][0]; y1 = a[0][1]; x2 = a[0][0]; y2 = a[0][1];
        for (var i=1;i<n;i++) {
            if (a[i][0] < x1) x1 = a[i][0];
            if (a[i][1] < y1) y1 = a[i][1];
            if (a[i][0] > x2) x2 = a[i][0];
            if (a[i][1] > y2) y2 = a[i][1];
        }
        var ok = 1;

        for (var i=0;i<n;i++) {
            if (a[i][0] > x1 && a[i][0] < x2 && a[i][1] > y1 && a[i][1] < y2) {
                ok = 0;
                break;
            }
        }
        if (ok) console.log('YES'); else console.log('NO');
    }
} 

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

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