Day 1:Let and Const.js

'use strict';

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', _ => {
    inputString = inputString.trim().split('\n').map(string => {
        return string.trim();
    });
    
    main();    
});

function readLine() 
{
    return inputString[currentLine++];
}
function main() 
{
    // Write your code here. Read input using 'readLine()' and print output using 'console.log()'.
    const r = readLine();
    const PI = Math.PI;
  //  area = Math.PI*r*r;
  //  perimeter = Math.PI*r*2;  
    console.log(PI*r*r);
    console.log(PI*r*2);

    try 
    {    
        // Attempt to redefine the value of constant variable PI
        PI = 0;
        // Attempt to print the value of PI
        console.log(PI);
    } 
    catch(error) 
    {
        console.error("You correctly declared 'PI' as a constant.");
    }
}