JavaScript How to make NPCs interact with only the first person to click on them.

[Groot]

var switch_name = npc.Id();
function init(hr, min, sec) {
    npc.setName("Seth");
    npc.warp("19,17",91,81);
};
function action(player) {
    function    var dialog = lib.dialog(player);
    dialog.talk("The hint is 1234");
    dialog.send();
};

So the above code is written for players to interact with NPCs. However what I want is for the NPC to interact with only the first player to click on it. What changes must be made?