Someone

new pvs_Vehicles[CAR_AMOUNT];

OnPlayerEnteredVehicle(playerID, vehicleid, ispassenger, OldDriverID)
{
new lKeys,Keys1,Keys2;

if (GetVehicleModel(vehicleid) == veh_Tram)
{
GetPlayerKeys(playerid, lKeys, Keys1, Keys2);
if (lKeys & KEY_SECONDARY_ATTACK)
{
	PutPlayerInVehicle(playerid, vehicleid, 0);
}
else {
for (new i = 1; i < 4; i++)
{
if (pvs_Vehicles[vehicleid] == INVALID_PLAYER_ID)
{
	PutPlayerInVehicle(playerid, vehicleid, i);
	pvs_Vehicles[vehicleid] ++;
break;
}
}
}
}

return PCOR_CONTINUE;
}