commit f7f6cadddc34d5e88d5169a36cf4565d17c918b5
Author: bot50 <bot@cs50.harvard.edu>
Date:   Fri Mar 22 12:36:58 2024 +0000

    kukemuna-cs50/problems/2024/x/sentimental/credit@20240322T123658.828443263Z

diff --git a/credit.py b/credit.py
new file mode 100644
index 0000000..d5e98e6
--- /dev/null
+++ b/credit.py
@@ -0,0 +1,60 @@
+import re
+import sys
+
+while True:
+    try:
+        card = input("Number: ").strip()  # Remove leading and trailing whitespaces
+        if card.isdigit():
+            break
+    except:
+        ValueError
+
+
+if not (len(card) == 13 or len(card) == 15 or len(card) == 16):
+    print("INVALID")
+    quit()
+
+
+cardNumber = int(card)
+numLength = len(card)
+id = int(card[0:4].splitlines()[0])
+
+
+sum = multiply = 0
+
+# Validate cardNumber with Luhn's Algorithm
+while (cardNumber > 0):
+    if (multiply):
+        if (cardNumber % 10 * 2 > 9):
+            n = cardNumber % 10 * 2
+            while (n > 0):
+                sum += int(n % 10)
+                n = int(n / 10)
+        else:
+            sum += cardNumber % 10 * 2
+        cardNumber = int(cardNumber / 10)
+        multiply = 0
+    else:
+        sum += cardNumber % 10
+        cardNumber = int(cardNumber / 10)
+        multiply = 1
+
+if (sum % 10 != 0):
+    print("INVALID")
+    quit()
+
+
+if ((int(id / 100) == 34 or int(id / 100) == 37) and numLength == 15):
+    print("AMEX")
+    quit()
+
+if ((int(id / 1000) == 4) and (numLength == 13 or numLength == 16)):
+    print("VISA")
+    quit()
+
+if (((int(id / 100) >= 51 and int(id / 100) <= 55) or (id >= 2221 and id <= 2720)) and numLength == 16):
+    print("MASTERCARD")
+    quit()
+
+else:
+    print("INVALID")