new NeedTickets[MAX_PLAYERS];
new HaveTickets[MAX_PLAYERS];
public OnPlayerEnterVehicle(playerid, vehicleid, ispassenger)
{
    new vehicle;
    vehicle = GetPlayerVehicleID(playerid);
    if(vehicle == 431 && ispassenger == 1)
    {
    if(NeedTickets[playerid] == 1)
    {
    GivePlayerMoney(playerid,-50);
    HaveTickets[playerid] = 1;
    }
    else if(GetPlayerMoney(playerid) < 50 && HaveTickets[playerid] == 0)
   {
   new Float:x;
   new Float:y;
   new Float:z;
    GetPlayerPos(playerid,x,y,z);
   SetPlayerPos(playerid,x,y,z);
   SendClientMessage(playerid,-1,"You don't have enough money for tickets");
}
    return 1;
}