for (let i = 0; i < a.length; i++) {
   console.log(a[i][0]);
}

parseFloat(document.getElementById('chislo1_2').value)

var express = require('express')
var cors = require('cors')
var app = express()

app.use(cors())

document.querySelector('.one').addEventListener('click', _=> {
	document.querySelector('.two').classList.toggle('three');
})