diff --git a/src/xs_ibdpcompsci_javaintro/calculator.java b/src/xs_ibdpcompsci_javaintro/calculator.java
index c90c1aa..3c00d2c 100644
--- a/src/xs_ibdpcompsci_javaintro/calculator.java
+++ b/src/xs_ibdpcompsci_javaintro/calculator.java
@@ -3,13 +3,27 @@ import java.util.*;
 import java.util.regex.Pattern;
 
 class RPN_Calculator {
+	static void line_clear(int TIMES) {
+		TIMES = Math.abs(TIMES);
+		
+		if (TIMES > 0) {
+			for (int CLEAR_INSTANCES = 0; CLEAR_INSTANCES < TIMES; CLEAR_INSTANCES++) {
+				System.out.print(String.format("\033[2K",2));
+				System.out.print(String.format("\033[%dA",2)); // Move up
+				System.out.print(String.format("\033[2K",2));
+				System.out.print("\n");
+			};
+		};
+	}
+
+
 	static void handle_error(int ERROR_TYPE) {
 		String ERROR_MESSAGE = "";
 		
 		switch (ERROR_TYPE) {
 			case -1:
 				// Delete the previous line to allow users to edit it. 
-				System.out.print("\r");
+				line_clear(1);
 				break;
 			case -2: 
 				ERROR_MESSAGE = "Memory exceeded.";
@@ -61,10 +75,12 @@ class RPN_Calculator {
 						USER_INPUTS.add(USER_INPUT_CURRENT);
 					} else {
 						// Correct the mathematical operator. 
-						System.out.print("\r\r"+ "> "+ USER_INPUT_CURRENT);
-						USER_INPUTS.set(USER_INPUT_LENGTH - 1, USER_INPUT_LENGTH);
+						line_clear(1);
+						System.out.print("> "+ USER_INPUT_CURRENT);
+						USER_INPUTS.set(USER_INPUT_LENGTH - 1, USER_INPUT_CURRENT);
 					};
 				} else if (USER_INPUT_CURRENT.isBlank() && USER_INPUTS.get(USER_INPUT_LENGTH - 1).getClass() == String.class) {
+					line_clear(1);
 					USER_INPUT_MORE = false;
 				} else {
 					handle_error(-1);
@@ -75,7 +91,6 @@ class RPN_Calculator {
 				// The user inputs a wrong code. Let the user edit it. 
 				handle_error(-1);
 			};
-			
 		} while (USER_INPUT_MORE == true);
 		
 		return (USER_INPUTS);
@@ -88,49 +103,47 @@ class RPN_Calculator {
 		String OPERATION = "";
 		double OPERATION_RESULT = 0;
 
-		ArrayList<Double> NUMBERS_CURRENT = new ArrayList<Double>();
+		Queue<Double> NUMBERS_CURRENT = new ArrayDeque<Double>();
 
 		// TO DO: fix entries search
 		if (ENTRIES_LIST_LENGTH > 1) {
 			for (int ENTRY_CURRENT = 0; ENTRY_CURRENT < ENTRIES_LIST_LENGTH; ENTRY_CURRENT++) {
 				if (String.valueOf(ENTRIES_LIST.get(ENTRY_CURRENT)).matches("[-+\\/*×÷]")) {
 					OPERATION = String.valueOf(ENTRIES_LIST.get(ENTRY_CURRENT));
-					if (OPERATION_ITERATIONS <= 0) {OPERATION_RESULT = NUMBERS_CURRENT.get(0); NUMBERS_CURRENT.remove(0);};
+					if (OPERATION_ITERATIONS <= 0) {OPERATION_RESULT = NUMBERS_CURRENT.poll();};
 
 					switch (OPERATION) {
 						case "*":
 						case "×":
-							for (Double NUMBER_CURRENT : NUMBERS_CURRENT) {
-								OPERATION_RESULT *= NUMBER_CURRENT;
-							};
+							do {
+								OPERATION_RESULT *= NUMBERS_CURRENT.poll();
+							} while (!NUMBERS_CURRENT.isEmpty());
 							break;
 						case "/":
 						case "÷": 
-							for (Double NUMBER_CURRENT : NUMBERS_CURRENT) {
-								if (NUMBER_CURRENT != 0) {
-									OPERATION_RESULT /= NUMBER_CURRENT;
-								} else {
-									handle_error(-3);
-									break;
-								};	
-							};
+							Double NUMBER_CURRENT = NUMBERS_CURRENT.poll();
+							if (NUMBER_CURRENT != 0) {
+								OPERATION_RESULT /= NUMBER_CURRENT;
+							} else {
+								handle_error(-3);
+								break;
+							};	
 							break;
 						case "+": 
-							for (Double NUMBER_CURRENT : NUMBERS_CURRENT) {
-								OPERATION_RESULT += NUMBER_CURRENT;
-							};
+							do {
+								OPERATION_RESULT += NUMBERS_CURRENT.poll();
+							} while (!NUMBERS_CURRENT.isEmpty());
 							break;
 						case "-": 
-							for (Double NUMBER_CURRENT : NUMBERS_CURRENT) {
-								OPERATION_RESULT -= NUMBER_CURRENT;
-							};
+							do {
+								OPERATION_RESULT -= NUMBERS_CURRENT.poll();
+							} while (!NUMBERS_CURRENT.isEmpty());
 							break;
 						default:
 							break;
 					};
 
 					OPERATION_ITERATIONS++;	
-					NUMBERS_CURRENT.clear();
 				} else {
 					NUMBERS_CURRENT.add((double) ENTRIES_LIST.get(ENTRY_CURRENT));
 				};
@@ -140,7 +153,6 @@ class RPN_Calculator {
 		return (OPERATION_RESULT);
 	};
 	
-	
 	public static void main(String[] args) {
 		// Initialize the input numbers. 
 		ArrayList<Object> NUMBERS_INPUT = new ArrayList<Object>();