While loop continuing after break condition met

My current assignment requires me to allow for a user to pass strings of characters and convert from roman numerals to a decimal value. I've hit an issue that when random words are passed through the program it must return the longest valid prefix and ignore the remaining characters, my code runs through a while loop and once it hits the break condition it repeats the code again for the remaining characters. I'm unsure what next step I should take to fix this code to output correctly. Following image shows the characters to pass through the code. Image of test failure

#include <iostream>
#include <ctype.h>

using namespace std;
int
main (){
   while (!cin.eof ()){
    char inputChar;
    int result = 0;
    while (cin.get (inputChar))
    {
        inputChar = toupper (inputChar);
        if (inputChar == 'M')
            result = result + 1000;
        else if (inputChar == 'D')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M')
            {
                result = result - 500;
                continue;
            }
            else if (inputChar == 'D'){
                result = result;
                continue;
            }
            else
            {
                result = result + 500;
                continue;
            }
        }
        else if (inputChar == 'C')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D')
            {
                result = result - 100;
                continue;
            }
            else
            {
                result = result + 100;
                continue;
            }
        }
        else if (inputChar == 'L')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C')
            {
                result = result - 50;
                continue;
            }
            else
            {
                result = result + 50;
                continue;
            }
        }
        else if (inputChar == 'X')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C'
                || inputChar == 'L')
            {
                result = result - 10;
                continue;
            }
            else
            {
                result = result + 10;
                continue;
            }
        }
        else if (inputChar == 'V')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C'
                || inputChar == 'L' || inputChar == 'X')
            {
                result = result - 5;
                continue;
            }
            else
            {
                result = result + 5;
                continue;
            }
        }
        else if (inputChar == 'I')
        {
            inputChar = cin.peek ();
            inputChar = toupper (inputChar);
            if (inputChar == 'M' || inputChar == 'D' || inputChar == 'C'
                || inputChar == 'L' || inputChar == 'X' || inputChar == 'V')
            {
                result = result - 1;
                continue;
            }
            else
            {
                result = result + 1;
                continue;
            }
        }
        else{
            break;
        }
    }
    if (result != 0)
    {
        cout << result << endl;
    }
}
return 0;
}