Roman numerals are represented by seven different symbols:

Symbol	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX.

There are six instances where subtraction is used:

• IV = 4, IX = 9
• XL = 40, XC = 90
• CD = 400, CM = 900

Given a roman numeral, convert it to an integer.

Examples

Example 1

Input:  s = "III"
Output: 3

Example 2

Input:  s = "LVIII"
Output: 58

L = 50, V = 5, III = 3

Example 3

Input:  s = "MCMXCIV"
Output: 1994

M = 1000, CM = 900, XC = 90, IV = 4

Constraints

• 1 <= s.length <= 15
• s contains only the characters ('I', 'V', 'X', 'L', 'C', 'D', 'M')
• It is guaranteed that s is a valid roman numeral in the range [1, 3999]