function selectCounsellor(img) {
    var i
    for (i = 1; i < 5; i++) {
        document.getElementById('c'+i).src = '/images/sils/c'+i+'.gif';
        document.getElementById('d'+i).style.display = 'none';
    }
    document.getElementById('c' + img).src = '/images/sils/c' + img + '_s.gif';
    document.getElementById('d' + img).style.display = 'block';
}