public static Role getMarketRole(int shift){
		Map<Role, Boolean> shiftRoles = sRolesFilled.get(shift);

		
		//MarketCashierRole (1) - first priority
		for (Role iRole : shiftRoles.keySet()){
			if (iRole instanceof MarketCashierRole){
				if (shiftRoles.get(iRole) == false){ //if role not filled
					shiftRoles.put(iRole, true);
					return (MarketCashierRole) iRole;
				}
			}
		}
		
		//MarketWorkerRole
		for (Role iRole : shiftRoles.keySet()){
			if (iRole instanceof MarketWorkerRole){
				if (shiftRoles.get(iRole) == false){ //if role not filled
					shiftRoles.put(iRole, true);
					return (MarketWorkerRole) iRole;
				}
			}
		}
		
		//MarketDeliveryTruckRole
		for (Role iRole : shiftRoles.keySet()){
			if (iRole instanceof MarketDeliveryTruckRole){
				if (shiftRoles.get(iRole) == false){ //if role not filled
					shiftRoles.put(iRole, true);
					return (MarketDeliveryTruckRole) iRole;
				}
			}
		}
		return null;
	}