diff --git a/com/xgiovio/StackCheckParenthesis.java b/com/xgiovio/StackCheckParenthesis.java
new file mode 100644
index 0000000..12ec6b4
--- /dev/null
+++ b/com/xgiovio/StackCheckParenthesis.java
@@ -0,0 +1,79 @@
+package com.xgiovio;
+
+import exceptions.EmpyStackException;
+import stack.SinglePointerStack;
+
+import java.util.Scanner;
+
+public class StackCheckParenthesis {
+
+    /////////////// questo programma controlla se una strng ain input ha correttaemnte le parentesi tonde e quadre
+
+    public static void main(String[] args) {
+
+        System.out.println("Stringa in input con () e []:");
+        Scanner reader = new Scanner(System.in);
+        String word = reader.nextLine();
+        boolean status = true;
+
+        SinglePointerStack<Character> stack = new SinglePointerStack<Character>();
+        try{
+        for (int i = 0;i< word.length();i++){
+
+             if (word.charAt(i)  != '(' && word.charAt(i)  != ')' && word.charAt(i)  != '[' && word.charAt(i)  != ']' ){
+                  continue;
+             }
+
+            if ( word.charAt(i)  == '(' ){
+              stack.push('(');
+
+              continue;
+            }
+
+            if ( word.charAt(i)  == ')'   ){
+                if (stack.top() == '(' ){
+                    stack.pop();
+                    continue;
+                } else{
+                    status = false;
+                    break;
+                }
+
+            }
+
+            if ( word.charAt(i)  == '[' ){
+                if (stack.isEmpty()){
+                    stack.push('[');
+                    continue;
+                }
+                if ( stack.top() == '(' ){
+                    status = false;
+                    break;
+                } else{
+                    stack.push('[');
+                    continue;
+                }
+            }
+
+            if ( word.charAt(i)  == ']' ){
+                if (stack.top() == '[' ){
+                    stack.pop();
+                    continue;
+                } else{
+                    status = false;
+                    break;
+                }
+            }
+
+        }
+        if (status && stack.isEmpty()) {
+            System.out.println("Stringa corretta"); }
+        else{
+            System.out.println("Stringa errata");
+        }
+        }
+        catch (EmpyStackException e){
+            System.out.println("Stringa errata");
+        }
+    }
+}
diff --git a/com/xgiovio/StackInvertString.java b/com/xgiovio/StackInvertString.java
new file mode 100644
index 0000000..6ea2cb0
--- /dev/null
+++ b/com/xgiovio/StackInvertString.java
@@ -0,0 +1,30 @@
+package com.xgiovio;
+
+import exceptions.EmpyStackException;
+import stack.SinglePointerStack;
+
+import java.util.Scanner;
+
+public class StackInvertString {
+
+    /////////////// questo programma inverte una stringa mediante stack
+
+    public static void main(String[] args) {
+
+        System.out.println("Stringa in input");
+        Scanner reader = new Scanner(System.in);
+        String word = reader.nextLine();
+        String word_inverted = "";
+
+        SinglePointerStack<Character> stack = new SinglePointerStack<Character>();
+        for (int i = 0;i< word.length();i++){
+             stack.push(word.charAt(i));
+        }
+        for (int i = 0;i< word.length();i++){
+            word_inverted = word_inverted.concat(String.valueOf(stack.pop()));
+        }
+
+            System.out.println(word_inverted); }
+
+
+    }
diff --git a/stack/SinglePointerStack.java b/stack/SinglePointerStack.java
index fcb75ff..9613d5e 100644
--- a/stack/SinglePointerStack.java
+++ b/stack/SinglePointerStack.java
@@ -37,6 +37,7 @@ public class SinglePointerStack<E> extends StackRules<E> {
         }else{
             to_return = stack;
             stack = stack.getNext();
+            --number_of_elements;
             return to_return.getElement();
         }
     }