function getSum() {
	r1 = document.getElementById('r1').value.replace(",",".");
	r2 = document.getElementById('r2').value.replace(",",".");
	r3 = document.getElementById('r3').value.replace(",",".");
	w1 = document.getElementById('w1').value.replace(",",".");
	w2 = document.getElementById('w2').value.replace(",",".");
	d1 = document.getElementById('d1').value.replace(",",".");
	d2 = document.getElementById('d2').value.replace(",",".");

	s = (r1*2 + r2*2)*r3;
	real = Math.ceil((s - (w1*w2 + d1*d2))*100)/100;

	document.getElementById('calc_val').style.display = 'block';
	document.getElementById('calc_val').value = 'Необходимо '+real+' кв.м. обоев';

}