Rimski brojevi (O)

#include <iostream>
using namespace std;

int rim_dek (string a)
{
    a = a + " ";
    string k = "";
    int s = 0;
    for (int i=0; i<a.length()-1; i++)
    {
        k = k + a[i];
        k = k + a[i+1];
        if (k=="IV")
        {s = s + 4; i++;}
        else if (k=="IX")
        {s = s + 9; i++;}
        else if (k=="XL")
        {s = s + 40; i++;}
        else if (k=="XC")
        {s = s + 90; i++;}
        else if (k=="CD")
        {s = s + 400; i++;}
        else if (k=="CM")
        {s = s + 900; i++;}
        else if (k=="IM")
        {s = s + 999; i++;}
        else if (k=="XM")
        {s = s + 990; i++;}
        else
        {
            switch (a[i])
            {
            case 'I': s = s + 1; break;
            case 'V': s = s + 5; break;
            case 'X': s = s + 10; break;
            case 'L': s = s + 50; break;
            case 'C': s = s + 100; break;
            case 'D': s = s + 500; break;
            case 'M': s = s + 1000; break;
            }
        }
        k="";
    }

    return s;
}

string dek_rim (int a)
{
       string s = "";

       while (a>=1000) { s = s + "M"; a = a - 1000; }
       while (a>=999) { s = s + "IM"; a = a - 999; }
       while (a>=990) { s = s + "XM"; a = a - 990; }
       while (a>=900) { s = s + "CM"; a = a - 900; }
       while (a>=500) { s = s + "D"; a = a - 500; }
       while (a>=400) { s = s + "CD"; a = a - 400; }
       while (a>=100) { s = s + "C"; a = a - 100; }
       while (a>=90) { s = s + "XC"; a = a - 90; }
       while (a>=50) { s = s + "L"; a = a - 50; }
       while (a>=40) { s = s + "XL"; a = a - 40; }
       while (a>=10) { s = s + "X"; a = a - 10; }
       while (a>=9) { s = s + "IX"; a = a - 9; }
       while (a>=5) { s = s + "V"; a = a - 5; }
       while (a>=4) { s = s + "IV"; a = a - 4; }
       while (a>=1) { s = s + "I"; a = a - 1; }

       return s;
}

main()
{
      int n;
      string s[101];

      cin >> n;
      for (int i=1; i<=n; i++)
          cin >> s[i];

      if (n%2==1)
         n = n - 1;

      for (int i=1; i<=n; i=i+2)
      {
          int a = rim_dek(s[i]) + rim_dek(s[i+1]);
          if (a<3999)
              cout << dek_rim(a) << endl;
          else
              cout << "Prekoracenje" << endl;
      }

      system("PAUSE");
}