diff --git a/medium/count_number_of_bad_pairs.py b/medium/count_number_of_bad_pairs.py
new file mode 100644
index 0000000..167b41c
--- /dev/null
+++ b/medium/count_number_of_bad_pairs.py
@@ -0,0 +1,13 @@
+# https://leetcode.com/problems/count-number-of-bad-pairs
+
+from typing import List
+
+class Solution:
+    def countBadPairs(self, nums: List[int]) -> int:
+        result = 0
+        counts = {}
+        for i in range(len(nums)):
+            zero_value = nums[i] - i
+            counts[zero_value] = counts.get(zero_value, 0) + 1
+            result += (i + 1) - counts[zero_value]
+        return result