let a = document.querySelector('.a'),
b = document.querySelector('.b'),
c = document.querySelector('.c');
const input = document.querySelector('.input')
let array = [a,b,c]
let pup = []
for (let element of array) {
element.addEventListener('click', (e)=>{
const [elementClass] = e.target.classList
pup.push(elementClass)
console.log(pup.join(''))
})
}