function toggleElem(index, prefix, n_elems) {
    
    for(var i = 1; i <= n_elems; i++) {
        var elem = document.getElementById(prefix + i);
        
        if(elem) {
            
            if(i == index)
                elem.style.display = ((elem.style.display == "none") ? "block" : "none");
            else
                elem.style.display = "none";
        }
    }
    
}