starter.js

process.stdin.resume();
process.stdin.setEncoding('utf8');

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++];
}

function print() {
    console.log.apply(null, arguments);
}

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

function greeting() {
    if (arguments.length > 0) {
        return 'Hello ' + arguments[0];
    }
    return 'Hello World';
}

// this serve as main entry to implement your solution
function main() {
    // write your code here.
    // call `readLine()` to read a line.
    // use print() to write to stdout

    print(
        greeting(readLine())
    );
}