diff --git a/exercises/1000_programs/medium/1876_good_substrings.py b/exercises/1000_programs/medium/1876_good_substrings.py
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+++ b/exercises/1000_programs/medium/1876_good_substrings.py
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+def good_substrings(s: str) -> int:
+    """
+    A substring is called good if all of the characters in the substring are different.
+
+    Given a string s, return the number of good substrings of length three in s.
+
+    Args:
+        s (str): The input string.
+
+    Returns: 
+        int: The number of good substrings of length three in s. 
+
+    Example: 
+        Input: s = "smithech"
+        Output: 6
+        Explanation: The good substrings are "smi", "mit", "ith", "the", "hec", "ech".
+    
+    """
+    count = 0
+
+    # len(s) - 2 because the last 3-character substring starts at index len(s)-3
+    for i in range(len(s) - 2):
+        # The set() function removes duplicate characters, so if the length of the set is 3, it means all characters are different
+        if len(set(s[i:i + 3])) == 3:
+            count += 1
+    return count
+
+if __name__ == "__main__":
+    example = "Smithech"
+    result = good_substrings(example)
+    print("Input: ", example)
+    print("Output: ", result) 
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