commit 2f658420eb793828bca7c89283405db3f0f297a6
Author: thanhtl <le.thanh1305@gmail.com>
Date:   Thu Nov 27 17:28:40 2025 +0700

    Add count.py

diff --git a/count.py b/count.py
new file mode 100644
index 0000000..5ef7c0c
--- /dev/null
+++ b/count.py
@@ -0,0 +1,24 @@
+# Mục đích là tìm dãy số thiếu trong dải number trong files numbers.txt
+# file name: find_missing_numbers.py
+
+def find_missing_numbers(filename, start=1, end=4384):
+    # Read all numbers from file
+    with open(filename, "r") as f:
+        numbers = set()
+        for line in f:
+            line = line.strip()
+            if line.isdigit():               # ensure it's a number
+                numbers.add(int(line))
+
+    # Generate full valid range
+    full_range = set(range(start, end + 1))
+
+    # Find what is missing
+    missing = sorted(full_range - numbers)
+
+    return missing
+
+
+# Example usage:
+missing_numbers = find_missing_numbers("numbers.txt")
+print("Missing numbers:", missing_numbers)