new PlayersConnected;

public OnPlayerConnect(playerid)
{
    if(!IsPlayerNPC(playerid))PlayersConnected++;
    //bloque de cуdigo
    return 1;
}
public OnPlayerDisconnect(playerid, reason)
{
    if(!IsPlayerNPC(playerid))PlayersConnected--;
    //bloque de cуdigo
    return 1;
}

CMD:slots(playerid, params[]){
    new string[128], Float:porcentaje;
    porcentaje = (PlayersConnected/GetMaxPlayers())*100;
    format(string, sizeof string, "Hay un porcentaje de %.2f slots vacнos y %.2f ocupados.", porcentaje, 100.0-porcentaje);
    return SendClientMessage(playerid, 0x00FF00FF, string), 1;
}