diff --git a/4.1.py b/4.1.py
new file mode 100644
index 0000000..27d4367
--- /dev/null
+++ b/4.1.py
@@ -0,0 +1,23 @@
+import re
+while True : 
+    x = input("Write a password : ")
+    try : 
+        assert len(x) >6 and len(x) <16, 'Your password must be between 6 and 16'
+        if not re.search("[a-z]", x):
+            raise ValueError('You must use at least a letter between [a,z]')
+        elif not re.search("[A-Z]", x):
+            raise ValueError('You must use at least a letter between [A-Z]')  
+        elif not re.search("[0-9]", x):
+            raise ValueError('You must use at least a number between [0-9]') 
+        elif not re.search("[#@$]", x):
+            raise ValueError('You must use special character')
+        
+    except ValueError as V : 
+        print(V)
+    except AssertionError as A:
+        print(A)
+    else : 
+        print("Successful Password.")
+        break
+    finally:
+        print("Have a Nice Day")
diff --git a/4.2.py b/4.2.py
new file mode 100644
index 0000000..e735721
--- /dev/null
+++ b/4.2.py
@@ -0,0 +1,17 @@
+import random as r
+import array as a
+
+dice = a.array('i', [0,0,0,0,0,0])
+rolledtimes = 0
+def roll():
+    rand = r.randrange(1,7)
+    return rand
+for i in range(1,5001):
+    number = roll()
+    dice.append(number)
+    rolledtimes+=1
+count = [dice.count(1),dice.count(2),dice.count(3),dice.count(4),dice.count(5),dice.count(6)]
+for i in range(0,6):
+    print('The probability is : ')
+    per = str("{:.2f}".format((count[i] / 5000)*100)) + '%'
+    print(i + 1, '>>', per)
diff --git a/4.3.main.py b/4.3.main.py
new file mode 100644
index 0000000..f340a49
--- /dev/null
+++ b/4.3.main.py
@@ -0,0 +1,10 @@
+import my_dice
+
+num = int(input("Enter repetition number: "))
+
+percentages = my_dice.rollDice(num)
+
+for i in range(6):
+    per = percentages[i]/num * 100
+    print("The probability of {} is {:.2f}".format(i+1, per))
+
diff --git a/4.4.py b/4.4.py
new file mode 100644
index 0000000..f149424
--- /dev/null
+++ b/4.4.py
@@ -0,0 +1,17 @@
+import math
+
+input_num = int(input("Please enter the number of inputs: "))
+
+gcd = int(input())
+
+for i in range(input_num-1):
+    try:
+        num = int(input())
+    except:
+        print("invalid input")
+    else:
+        gcd = math.gcd(gcd, num)
+        
+print("greatest common divisor", gcd)
+
+
diff --git a/my_dice.py b/my_dice.py
new file mode 100644
index 0000000..0bbf20e
--- /dev/null
+++ b/my_dice.py
@@ -0,0 +1,8 @@
+import random
+
+def rollDice(number):
+    dice = [0] * 6
+    for i in range(number):
+        x = random.randint(1,6)
+        dice[x-1] = dice[x-1] + 1
+    return dice