function show_leader(id) {
    var leaders = document.getElementsByClassName("hidden");
    for (var i=0;i<leaders.length;i++) {
        leaders[i].style.display = 'none';
    }
    var leader_imgs = document.getElementsByClassName("hidden_img");
    for (var i=0;i<leader_imgs.length;i++) {
        leader_imgs[i].style.display = 'none';
    }
    document.getElementById('leader'+id).style.display = 'block';
    document.getElementById('leader_img'+id).style.display = 'block';
}