function a(){
    alert("Привет!");
}
a()
//
function cube(){
    console.log(prompt(`число`)**3);
}
cube();
//
function avg2 (a, b){
    console.log((a + b) / 2);
}
avg2(1,2);
avg2(10,5);

//
function sum3 (a, b, c){
        a = a || 0;
        b = b || 0;
        c = c || 0;
        return(a + b + c);
}
sum3(1,2,3);
sum3(5,10,100500);
sum3(5,10);  

//
function intRandom (a, b){
        a = a || 0;
        b = b || 0;
        let number = (Math.random() * (b - a) + a);
        return Math.round(number);
}
console.log(intRandom(2, 15))
console.log(intRandom(-1, -1))
console.log(intRandom(0, 1))
console.log(intRandom(10))

//
function greetAll() {
    for(let i of arguments) {
       alert(`Hello ${i}`)
    }
 }
 greetAll("Superman")
 greetAll("Superman", "SpiderMan")
 greetAll("Superman", "SpiderMan", "Captain Obvious")

 //
 function sum (){
    let resulta = 0;
    for(let i of arguments){
        resulta += i;
    }
    console.log(resulta);
 }
sum(1)
sum(2)
sum(10, 20, 40, 100)
//

function aSample(){
    a("Привет!") // вызывает alert("Привет!")
}

function cubeSample(){
    cube(5) // => 125
}

let sample = prompt("Введите название задания")
switch (sample.toLowerCase()){
    case "a": a()
              break
    case "cube": cube()
              break
    case "avg2": avg2()
              break
    case "sum3": sum3()
              break
    case "intRandom": intRandom()
              break
    case "greetAll": greetAll()
              break
    case "sum": sum()
              break              
}

//
let sampl = {
    a: a(),
    cube: cube(),
    avg2: avg2(),
    sum3: sum3(),
    intRandom: intRandom(),
    greetAll: greetAll(),
    sum: sum()
}
let sampl1 = prompt("Введите название функции")
alert(sampl1[`${sampl}`])