function checkForm_en() {
	var name    = document.getElementById('name');
	var email   = document.getElementById('email');
	var phone   = document.getElementById('phone');
	var message = document.getElementById('message');
	
	if (!name.value.length && !email.value.length && !phone.value.length && !message.value.length) {
		return false;
	}
	if (!name.value.length) {
		alert('Please fill the field Name!');
		return false;
	}
	if (!email.value.length) {
		alert('Please fill the field Email!');
		return false;
	}
	var email_pattern = new RegExp("^[0-9A-Za-z_.-]+@[A-Za-z0-9_-]+[.][A-Za-z]{2,4}$", "i");
	if (!email_pattern.test(email.value)) {
		alert('Wrong email address!');
		return false;
	}
	if (!phone.value.length) {
		alert('Please fill the field Phone!');
		return false;
	}
	if (!message.value.length) {
		alert('Please fill the field Message!');
		return false;
	}
	return true;
}

function checkForm_de() {
	var name    = document.getElementById('name');
	var email   = document.getElementById('email');
	var phone   = document.getElementById('phone');
	var message = document.getElementById('message');
	
	if (!name.value.length && !email.value.length && !phone.value.length && !message.value.length) {
		return false;
	}
	if (!name.value.length) {
		alert('Please fill the field Name!');
		return false;
	}
	if (!email.value.length) {
		alert('Please fill the field Email!');
		return false;
	}
	var email_pattern = new RegExp("^[0-9A-Za-z_.-]+@[A-Za-z0-9_-]+[.][A-Za-z]{2,4}$", "i");
	if (!email_pattern.test(email.value)) {
		alert('Wrong email address!');
		return false;
	}
	if (!phone.value.length) {
		alert('Please fill the field Phone!');
		return false;
	}
	if (!message.value.length) {
		alert('Please fill the field Message!');
		return false;
	}
	return true;
}