////// WORKIGN CODE ////

var firstVar , secondVar , thridVar , forthVar;

firstVar = prompt('Enter The First Value of Series!!!');
secondVar = prompt(firstVar + ',');
thridVar = prompt(firstVar + ',' +secondVar + ',');
forthVar = prompt(firstVar + ',' +secondVar + ',' + thridVar + ',');


var check ;

if (  secondVar - firstVar === forthVar - thridVar  ) 
    {
        check = 0;
    }
else if(secondVar / firstVar === forthVar / thridVar )
        
    {
        check = 2;
    }
else if(secondVar * firstVar === forthVar * thridVar ) 
    {
        check = 3;
    }
else if(secondVar + firstVar === forthVar + thridVar ) 
    {
        check = 1;
    }



switch ( check ) {
    case 0:
        console.log('This series is maid by Substion tech:');
        break;
    case 1:
        console.log('This series is maid by Addition tech:');
        break;
    case 2:
        console.log('This series is maid by Division tech:');
        break;
    case 3:
        console.log('This series is maid by Multiplication tech:');
        break;
    default:
        console.log('Invalid Series!!!');
}



//////////// Not Working CODE.


var firstVar , secondVar , thridVar , forthVar;

firstVar = prompt('Enter The First Value of Series!!!');
secondVar = prompt(firstVar + ',');
thridVar = prompt(firstVar + ',' +secondVar + ',');
forthVar = prompt(firstVar + ',' +secondVar + ',' + thridVar + ',');


var check ;

switch (
    
(secondVar - firstVar === forthVar - thridVar ? 0 : null ) ||
(secondVar + firstVar === forthVar + thridVar ? 1 : null)  ||
(secondVar / firstVar === forthVar / thridVar ? 2 : null )  ||
(secondVar * firstVar === forthVar * thridVar ? 3 : null )


) {
    case 0:
        console.log('This series is maid by Substion tech:');
        break;
    case 1:
        console.log('This series is maid by Addition tech:');
        break;
    case 2:
        console.log('This series is maid by Division tech:');
        break;
    case 3:
        console.log('This series is maid by Multiplication tech:');
        break;
    default:
        console.log('Invalid Series!!!');
}