function processData(input) {
     var inputs = input.split("\n");
    var testCases = inputs.shift();
    var N;
    for (var test=0; test < testCases; test++){
        N = inputs.shift();
        var coordinates = [];
        for (var i = 0; i < N; i++){
            coordinates[i] = inputs.shift().split(" ");
            coordinates[i][0] = parseFloat(coordinates[i][0]);
            coordinates[i][1] = parseFloat(coordinates[i][1]);
            
        }
        var xMin=coordinates[0][0], xMax=coordinates[0][0], yMin=coordinates[0][1], yMax=coordinates[0][1];
        for (n in coordinates){
            if (coordinates[n][0] < xMin) { xMin = coordinates[n][0]}
            if (coordinates[n][0] > xMax) { xMax = coordinates[n][0]}
            if (coordinates[n][1] < yMin) { yMin = coordinates[n][1]}
            if (coordinates[n][1] > yMax) { yMax = coordinates[n][1]}
        }
        var isValid = "YES";
        for (n in coordinates){
            if (coordinates[n][0] != xMin && coordinates[n][0] != xMax && coordinates[n][1] != yMin && coordinates[n][1] != yMax){
                isValid ="NO";
                break;
            }
        }
        console.log(isValid);
    } 
} 

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

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