#####solution1####faster####

def romanToInt(s):

    d={

        'I':1,

        'V':5,

        'X':10,

        'L':50,

        'C':100,

        'D':500,

        'M':1000

    }

    i = 1

    count = last = d[s[0]]

    while i < len(s):

        current = d[s[i]]

        if current > last:

            count -= last * 2

        count += current

        last = current

        i += 1

    return count

# ########solution2########

# def romanToInt(s):

#     d = {'I': 1,

#          'V': 5,

#          'X': 10,

#          'L': 50,

#          'C': 100,

#          'D': 500,

#          'M': 1000

#          }

#     res = 0

#     if len(s) < 2:

#         return d[s[0]]

#     res = res + d[s[0]]

#     for i in range(1,len(s)):

#         res = res + d[s[i]]

#         if d[s[i]] > d[s[i - 1]]:

#             res = res - 2 * d[s[i-1]]

#     return res

#

#

# if __name__=='__main__':

#     m="MCMXCIV"

#     print(romanToInt(m))