'''

Question:

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M and their values are 1,5,10,50,100,500,1000 respectively.Given a roman numeral,convert it to an integer.Input is guaranteed to be within the range from 1 to 3999.

Example 1:

Input : 'XI'

Output : 11

Example 2:

Input : 'CCCXL'

Output : 340

Source: Interview question.

Time Complexity : O(n)

Space Complexity : O(1)

'''

# Function to convert a roman numeral to an integer

def roman_to_integer(input):

romans={'I':1,'V':5,'X':10,'L':50,'C':100,'D':500,'M':1000}

sum=0

for i in range(input):

# Getting the value of the symbol

value=romans[input[i]]

# Comparing if the next value is bigger or smaller than the current value

if i+1<len(input):

if romans[input[i+1]]>value:

# If it is big, the value is subtracted from the sum

sum-=value

else:

sum+=value

return sum

# Main code

print("Roman to integer conversion of")

input=input.upper()

roman_to_integer(input)