diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 0000000..5570fe5
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,12 @@
+{
+    "configurations": [
+        {
+            "type": "java",
+            "name": "Launch BankController",
+            "request": "launch",
+            "mainClass": "bank.BankController",
+            "projectName": "Lab15_OOP_90898795",
+            "vmArgs": "-enableassertions"
+        }
+    ]
+}
\ No newline at end of file
diff --git a/bin/bank/BankAccount.class b/bin/bank/BankAccount.class
index 326e506..97add34 100644
Binary files a/bin/bank/BankAccount.class and b/bin/bank/BankAccount.class differ
diff --git a/bin/bank/Checking.class b/bin/bank/Checking.class
index 2474003..f745778 100644
Binary files a/bin/bank/Checking.class and b/bin/bank/Checking.class differ
diff --git a/bin/bank/Savings.class b/bin/bank/Savings.class
index 7712331..2f9c7b3 100644
Binary files a/bin/bank/Savings.class and b/bin/bank/Savings.class differ
diff --git a/src/bank/BankAccount.java b/src/bank/BankAccount.java
index 0933b8e..c914dc8 100644
--- a/src/bank/BankAccount.java
+++ b/src/bank/BankAccount.java
@@ -8,18 +8,27 @@ public abstract class BankAccount {
         return balance;
     }
     public void deposit(double amount){
+        if(amount<0){
+            error("cannot deposit this amount !");
+            return;
+        } 
         balance += amount;
     }
     public boolean withdraw(double amount){
         if(balance<amount){
-            System.out.println("Problem : cannot withdraw that amount");
-            return false;
+            return error("cannot withdraw this amount !");
         } 
-        
         balance -= amount;
         return true;
     }
 
+    protected boolean error(String text){
+        System.out.println("Problem : " + text);
+        return false;
+    }
+    
+
+
     @Override
     public String toString() {
         return owner + " have " + balance + "CHF on his account.";
diff --git a/src/bank/Checking.java b/src/bank/Checking.java
index de341f6..10be86c 100644
--- a/src/bank/Checking.java
+++ b/src/bank/Checking.java
@@ -3,15 +3,40 @@ package bank;
 public class Checking extends BankAccount{
     private double minBalance;
 
-    Checking(String owner, double amount, double minBalance){
+    protected Checking(String owner, double amount, double minBalance){
+        if(owner==null){
+            error("An account have to be an owner");
+            return;
+        }
+        if(amount<minBalance){
+            error("Not enough money");
+            return;
+        }
+        if(minBalance>0){
+            error("Min balance can't be positive");
+            return;
+        }
         this.owner = owner;
         this.balance = amount;
         this.minBalance = minBalance;
     }
-    public void setMinBalance(double minBalance) {
+    protected void setMinBalance(double minBalance) {
+        if(minBalance>0){
+            error("Min balance can't be positive");
+            return;
+        }
         this.minBalance = minBalance;
     }
     public double getMinBalance() {
         return minBalance;
     }
+
+    @Override
+    public boolean withdraw(double amount){
+        if((balance-minBalance)<amount){
+            return error("cannot withdraw this amount !");
+        } 
+        balance -= amount;
+        return true;
+    }
 }
diff --git a/src/bank/Savings.java b/src/bank/Savings.java
index 6aea0db..9a4db41 100644
--- a/src/bank/Savings.java
+++ b/src/bank/Savings.java
@@ -5,13 +5,26 @@ import java.util.Date;
 
 public class Savings extends BankAccount{
     private double interestRate;
-    Savings(String owner, double amount, double interestRate){
+    protected Savings(String owner, double amount, double interestRate){
+        if(owner==null){
+            error("An account have to be an owner");
+            return;
+        }
+        if(amount<0) {
+            error("A Saving account can't have a negative amount");
+            return;
+        }
+        if(interestRate<0){
+            error("cannot have interest negative");
+            return;
+        }
         this.owner = owner;
         this.balance = amount;
         this.interestRate = interestRate;
     }
-    public double calcInterest(Date a, Date b){
-        int day = DateUtils.nDays(a, b);
-        return interestRate * (day/360.0);
+    
+    protected double calcInterest(Date a, Date b){
+        double days = DateUtils.nDays(a, b);
+        return balance * interestRate * (days/360.0);
     }
 }