#include <iostream>
#include <string>
using namespace std;
int main(int argc, char* argv[])
{
    const int M = 1000;
    const int D = 500;
    const int C = 100;
    const int L = 50;
    const int X = 10;
    const int V = 5;
    const int I = 1;
    int nNum;
    cout<<"Input number: ";
    cin>>nNum;
    int nM = nNum/M;
    int nRemainM = nNum%M;
    int nD = nRemainM/D;
    int nRemainD = nRemainM%D;
    int nC = nRemainD/C;
    int nRemainC = nRemainD%C;
    int nL = nRemainC/L;
    int nRemainL = nRemainC%L;
    int nX = nRemainL/X;
    int nRemainX = nRemainL%X;
    int nV = nRemainX/V;
    int nRemainV = nRemainX%V;
    int nI = nRemainV;
    int i;
    for(i = 0; i < nM; i++)
        cout<<"M";
    for(i = 0; i < nD; i++)
        cout<<"D";
    for(i = 0; i < nC; i++)
        cout<<"C";
    for(i = 0; i < nL; i++)
        cout<<"L";
    for(i = 0; i < nX; i++)
        cout<<"X";
    for(i = 0; i < nV; i++)
        cout<<"V";
    for(i = 0; i < nI; i++)
        cout<<"I";
    cout<<"\n";
    return 0;
}
int get_arab_num(std::string rom_str)
{
    int res = 0;
    for(size_t i = 0; i < rom_str.length(); ++i)
    {
        switch(rom_str[i])
        {
        case 'M': 
            res += 1000;
            break;
        case 'D': 
            res += 500;
            break;
        case 'C':
            i + 1 < rom_str.length() 
                    &&  (rom_str[i + 1] == 'D' 
                         || rom_str[i + 1] == 'M') ? res -= 100 : res += 100;            
            break;
        case 'L': 
            res += 50;
            break;
        case 'X': 
            i + 1 < rom_str.length() 
                    &&  (rom_str[i + 1] == 'L' 
                         || rom_str[i + 1] == 'C') ? res -= 10 : res += 10;            
            break;
        case 'V': 
            res += 5;
            break;
        case 'I': 
            i + 1 < rom_str.length() 
                    &&  (rom_str[i + 1] == 'V' 
                         || rom_str[i + 1] == 'X') ? res -= 1 : res += 1;            
            break;
 
        }//switch
    }//for
    return res;
} 
int main()
{
    std::string s;
    for(;;)
    {
        std::cout << "input roman num: ";
        std::cin >> s;
        std::cout 
            << "arab num = "
            << get_arab_num(s)
            << std::endl
            << std::endl;
    }
    return 0;
}