function show_section (num) {
	var div;
	var section_num = 0;
	while (true) {
		div = document.getElementById('section' + section_num);
		if (!div) {
			break;
		}
		div.style.display = 'none';
		section_num = section_num + 1;
	}
	div = document.getElementById('section' + num);
	div.style.display = 'block';
	return false;
}