process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
    var n = parseInt(readLine()),
        points = [],
        lineX = 0,
        lineY = 0;
    for(var a0 = 0; a0 < n; a0++){
        var x_temp = readLine().split(' ');
        var x = parseInt(x_temp[0]);
        var y = parseInt(x_temp[1]);
        
        if(a0 == 0){
            lineX = x;
            lineY = y;
        }
        points.push([x,y]); 
    }
    
    var isHoriORVerti = function( element ){
            var x = element[0],
                y = element[1];
            
            return ( x == lineX || y == lineY );
        
    };
    console.log(points.every(isHoriORVerti)? "YES" : "NO");
}