Pomodoro clock doesnt stop when the break time is 0

after a couple of days researching and struggling with this project i would like to ask for some help. The piece of code that doesnt get executed is the last one where the breaktime should stop when is 0 running the clearInterval method.

Also the I dont know how prevent the countdown to be executed multiple times when you click inside the red circle.

I´m a newbie so the code is as primitive as it gets but i´m trying.

Codepen link: https://codepen.io/Seonatic/pen/zRPygV

function countdown(){

var session = document.getElementById(“count”).value;
var time = document.getElementById(“input”).value =+session60;
var breakm = document.getElementById(“break”).value;
var breaktime =document.getElementById(“input”).value =+breakm
var display = document.getElementById(“input”).value;
var sec = 1;

var myVar = setInterval(myTimer, 1000);

function myTimer(){
document.getElementById(“input”).value = time–;

var myVar2 = setInterval(increase, 1000);
function increase(){
document.getElementById(“input”).value = breaktime–;
if (breaktime===0) {