#include <iostream>
#include <stack>
#include <cmath>

using namespace std;
#define in(v) v; cin >> v;
#define rep(i,n) for(int i=0,_i=(n);i<_i;++i)
#define rrep(i,n) for(int i=(n);i>=0;--i)

int main() {
  int N; cin >> N;

  int ans = 0;
  char cur[5] = {'I', 'X', 'C', 'M', ' '}, mid[4] = {'V', 'L', 'D', ' '};
  rep(i, N) {
    string in(a);
    int idx = 0;
    rrep(j, 3) {
      int k = idx;
      while (k < a.size() && (a[k] == cur[j] || a[k] == mid[j] || a[k] == cur[j+1]))
        ++k;
      string S = a.substr(idx, k-idx); idx = k;
      int n;
      if (S == string(1, cur[j]) + cur[j+1])    n = 9;
      else if (S == string(1, cur[j]) + mid[j]) n = 4;
      else if (S.find(mid[j]) == string::npos)  n = S.length();
      else n = S.length() + 4;
      ans += n * pow(10, j);
    }
  }
  if (ans > 3999) {
    cout << "ERROR\n";
    return 0;
  }
  stack<string> ans_s;
  rep(i, 4) {
    int n = ans % 10; ans /= 10;
    string s;
    if (n == 9)
      (s += cur[i]) += cur[i+1];
    else if (n == 4)
      (s += cur[i]) += mid[i];
    else {
      if (n >= 5)
        n -= 5, s += mid[i];
      rep(k, n)
        s += cur[i];
    }
    ans_s.push(s);
  }
  while (!ans_s.empty()) {
    cout << ans_s.top(); ans_s.pop();
  }
  cout << endl;

  return 0;
}