#include <iostream>
#include <string>
#include <stack>
#include <map>
#include <vector>
#include <algorithm>
using namespace std;

int roman_to_int(const string &s) {
    map<char, int> value;
    value['I'] = 1;
    value['V'] = 5;
    value['X'] = 10;
    value['L'] = 50;
    value['C'] = 100;
    value['D'] = 500;
    value['M'] = 1000;

    int result = 0;
    int prev = 0;
    for (int i = s.size() - 1; i >= 0; --i) {
        int curr = value[s[i]];
        if (curr < prev)
            result -= curr;
        else
            result += curr;
        prev = curr;
    }
    return result;
}

string int_to_roman(int num) {
    vector<pair<int, string> > roman;
    roman.push_back(make_pair(1000, "M"));
    roman.push_back(make_pair(900, "CM"));
    roman.push_back(make_pair(500, "D"));
    roman.push_back(make_pair(400, "CD"));
    roman.push_back(make_pair(100, "C"));
    roman.push_back(make_pair(90, "XC"));
    roman.push_back(make_pair(50, "L"));
    roman.push_back(make_pair(40, "XL"));
    roman.push_back(make_pair(10, "X"));
    roman.push_back(make_pair(9, "IX"));
    roman.push_back(make_pair(5, "V"));
    roman.push_back(make_pair(4, "IV"));
    roman.push_back(make_pair(1, "I"));

    string result = "";
    for (int i = 0; i < roman.size(); ++i) {
        while (num >= roman[i].first) {
            result += roman[i].second;
            num -= roman[i].first;
        }
    }
    return result;
}

int main() {
    string input;
    stack<int> stk;

    while (cin >> input) {
        if (input == "+" || input == "-" || input == "*" || input == "/") {
            if (stk.size() < 2) {
                cout << "stack underflow" << endl;
                continue;
            }
            int a = stk.top(); stk.pop();
            int b = stk.top(); stk.pop();

            if (input == "+") stk.push(b + a);
            else if (input == "-") stk.push(b - a);
            else if (input == "*") stk.push(b * a);
            else if (input == "/") {
                if (a == 0) {
                    cout << "division by zero exception" << endl;
                    stk.push(b);
                } else {
                    stk.push(b / a);
                }
            }
        } else if (input == "=") {
            if (stk.empty()) {
                cout << "stack underflow" << endl;
            } else {
                int val = stk.top();
                if (val <= 0 || val > 4999) {
                    cout << "out of range exception" << endl;
                } else {
                    cout << int_to_roman(val) << endl;
                }
            }
        } else {
            stk.push(roman_to_int(input));
        }
    }

    return 0;
}