diff --git a/conversions/roman_numerals.py b/conversions/roman_numerals.py
index 75af2ac72..422c4ead6 100644
--- a/conversions/roman_numerals.py
+++ b/conversions/roman_numerals.py
@@ -1,61 +1,56 @@
 ROMAN = [
-    (1000, "M"),
-    (900, "CM"),
-    (500, "D"),
-    (400, "CD"),
-    (100, "C"),
-    (90, "XC"),
-    (50, "L"),
-    (40, "XL"),
-    (10, "X"),
-    (9, "IX"),
-    (5, "V"),
-    (4, "IV"),
-    (1, "I"),
+    (1000000, "M_"), (900000, "C_M_"), (500000, "D_"), (400000, "C_D_"),
+    (100000, "C_"), (90000, "X_C_"), (50000, "L_"), (40000, "X_L_"),
+    (10000, "X_"), (9000, "I_X_"), (5000, "V_"), (4000, "I_V_"),
+    (1000, "M"), (900, "CM"), (500, "D"), (400, "CD"),
+    (100, "C"), (90, "XC"), (50, "L"), (40, "XL"),
+    (10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I")
 ]
-
-
 def roman_to_int(roman: str) -> int:
     """
-    LeetCode No. 13 Roman to Integer
-    Given a roman numeral, convert it to an integer.
-    Input is guaranteed to be within the range from 1 to 3999.
-    https://en.wikipedia.org/wiki/Roman_numerals
-    >>> tests = {"III": 3, "CLIV": 154, "MIX": 1009, "MMD": 2500, "MMMCMXCIX": 3999}
+    Convert a Roman numeral to an integer, supporting Vinculum notation (underscore _ represents 1000 times).
+    LeetCode No. 13 Roman to Integer 
+ ​    Given a roman numeral, convert it to an integer. 
+ ​    Input is guaranteed to be within the range from 1 to 3999. 
+ ​    https://en.wikipedia.org/wiki/Roman_numerals 
+ ​    >>> all(roman_to_int(key) == value for key, value in tests.items())
+    >>> tests = {"III": 3, "CLIV": 154, "MIX": 1009, "MMD": 2500, "MMMCMXCIX": 3999, "I_V_": 4000, "X_": 10000, "M_": 1000000}
     >>> all(roman_to_int(key) == value for key, value in tests.items())
     True
     """
-    vals = {"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}
-    total = 0
-    place = 0
-    while place < len(roman):
-        if (place + 1 < len(roman)) and (vals[roman[place]] < vals[roman[place + 1]]):
-            total += vals[roman[place + 1]] - vals[roman[place]]
-            place += 2
+    vals = {
+    "I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000,
+        "I_": 1000, "V_": 5000, "X_": 10000, "L_": 50000, "C_": 100000, "D_": 500000, "M_": 1000000
+    }
+    i, total = 0, 0
+    while i < len(roman):
+        if i + 1 < len(roman) and (roman[i:i+2] in vals):  # 处理 `_` 记法
+            total += vals[roman[i:i+2]]
+            i += 2
         else:
-            total += vals[roman[place]]
-            place += 1
+            total += vals[roman[i]]
+            i += 1
     return total
-
-
-def int_to_roman(number: int) -> str:
+    def int_to_roman(number: int) -> str:
     """
-    Given a integer, convert it to an roman numeral.
-    https://en.wikipedia.org/wiki/Roman_numerals
-    >>> tests = {"III": 3, "CLIV": 154, "MIX": 1009, "MMD": 2500, "MMMCMXCIX": 3999}
+   Convert an integer to a Roman numeral, supporting Vinculum notation (underscore _ represents 1000 times).
+    Given a integer, convert it to an roman numeral. 
+ ​    https://en.wikipedia.org/wiki/Roman_numerals
+    >>> tests = {"III": 3, "CLIV": 154, "MIX": 1009, "MMD": 2500, "MMMCMXCIX": 3999, "I_V_": 4000, "X_": 10000, "M_": 1000000}
     >>> all(int_to_roman(value) == key for key, value in tests.items())
     True
     """
+    if not isinstance(number, int) or number < 1:
+        raise ValueError("Input must be a positive integer greater than 0")
+
     result = []
     for arabic, roman in ROMAN:
-        (factor, number) = divmod(number, arabic)
+        factor, number = divmod(number, arabic)
         result.append(roman * factor)
         if number == 0:
-            break
+        reak
     return "".join(result)
 
-
 if __name__ == "__main__":
     import doctest
-
     doctest.testmod()