// a

function a(){
    alert("Hello")
}
a();

// cube

function cube(x){
    return x**3;
    }
    
cube();

// avg2

function avg2(a,b){
    return (a + b)/2
}

avg2();

// sum3

function sum3(a,b,c){
    return (a + b + c) || (a + b) 
}
sum3();

// intRandom

function intRandom(a,b) {
    if(b === undefined){
     c = (Math.round(Math.random() *a))
    }else 
    c = (Math.round(Math.random() * (b - a) + a));
 return c
    }
intRandom()

greetAll 
function greetAll(){
    let guys = "";
    for(i = 0;i<arguments.length;i++){
        guys+=  "," +  " " + arguments[i]};
        alert(`Hi ${guys}`)

}


// sum

function sum(){
    let result = 0;
       for(i = 0;i<arguments.length;i++){
     result += arguments[i]};
   return result
   }
   sum()

//    Union

function aSample(){
   return a()
};

function cubeSample(){
    return cube(2)
};

function avg2Sample(){
   return avg2(3,4)
};

function sum3Sample(){
   return sum3(5,6,7)
};

function randomSample(){
   return intRandom(8,12)
};

function greetSample(){
   return greetAll("Oleg","Jopa")
};

function sumSample(){
  return  sum(9,10,11,12,13)
};

let sample = prompt('Введите задание');
switch(sample.toLowerCase()){
    case "a": aSample()
         break
    case "cube": cubeSample()
         break
    case "avg2": avg2Sample()
         break
    case "sum3": sum3Sample()
         break
    case "intRandom": randomSample()
         break
    case "greetAll": greetSample()
         break
    case "sum": sumSample()
         break
}



// Union declarative ?


let samplee = {
    "a": aSample(),
    "cube": cubeSample(),
    "avg2": avg2Sample(),
    "sum3": sum3Sample(),
    "intRandom": randomSample(),
    "greetAll": greetSample(),
    "sum": sumSample()
}
let qvest = prompt('Какая функция?')
alert(samplee[qvestion])