Roman Numerals1

#include<bits/stdc++.h>

using namespace std;

map<int,string>DecimalToRoman;

string R,s;

void DtoR(int value)
{
    DecimalToRoman[1000] = "M";
    DecimalToRoman[900] = "CM";

    DecimalToRoman[500] = "D";
    DecimalToRoman[400] = "CD";

    DecimalToRoman[100] = "C";
    DecimalToRoman[90] = "XC";

    DecimalToRoman[50] = "L";
    DecimalToRoman[40] = "XL";

    DecimalToRoman[10] = "X";
    DecimalToRoman[9] = "IX";

    DecimalToRoman[5] = "V";
    DecimalToRoman[4] = "IV";

    DecimalToRoman[1] = "I";

    map<int,string>::reverse_iterator it;

    s = "";

    for(it = DecimalToRoman.rbegin(); it!=DecimalToRoman.rend(); it++)
    {
        while(value>=it->first)
        {
            s+=(string) it->second;

            value-=it->first;
        }
    }
}

int main()
{
    int len,i,value,tot;

    while(cin>>R)
    {
        len = R.length();

        value = 0;

        tot = 0;

        for(i=0; i<len; i++)
        {
            value = value*10+(R[i]-48);
        }

        DtoR(value);

        len = s.length();

        for(i=0;i<len;i++)
        {
            if(s[i]=='I')
            {
                tot+=1;
            }
            else if(s[i]=='V'||s[i]=='X'||s[i]=='L'||s[i]=='C')
            {
                tot+=2;
            }
            else if(s[i]=='D')
            {
                tot+=3;
            }
            else if(s[i]=='M')
            {
                tot+=4;
            }
        }

        cout<<tot<<endl;
    }

    return 0;
}