Given an integer value n in the range [1, 3999], return its Roman numeral representation as a string. Roman numerals are constructed using the following symbols and values: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtractive forms are used for 4 (IV), 9 (IX), 40 (XL), 90 (XC), 400 (CD), and 900 (CM). Only the symbols I, X, C, and M can be repeated up to three times. For other values, use the subtractive form as needed.
Example 1
Input: n=2421
Output: MMCDXXI
Explanation: 2000 = MM, 400 = CD, 20 = XX, 1 = I
Example 2
Input: n=83
Output: LXXXIII
Explanation: 50 = L, 30 = XXX, 3 = III
Example 3
Input: n=999
Output: CMXCIX
Explanation: 900 = CM, 90 = XC, 9 = IX
Constraints
Case 1
Input: n=2768
Expected: 'MMDCCLXVIII'
Case 2
Input: n=145
Expected: 'CXLV'
Case 3
Input: n=3210
Expected: 'MMMCCX'
Case 4
Input: n=4
Expected: 'IV'
Case 5
Input: n=3888
Expected: 'MMMDCCCLXXXVIII'