#include <cstdio>
#include <climits>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <string>
#include <cstdio>
#include <climits>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <utility>
#include <queue>
#include <cstring>
#include <set>
#include <map>
#include <complex>
#define rep(i, n) for (int i = 0; i < int(n); i++)
using namespace std;
long long MOD = 998244353;
long long INF = 1000000000000000; //10^15
typedef long long ll;
typedef unsigned long long ull;


ll powMod(ll x, ll n, ll mod) {
  if (n == 0) return 1;
  ll t = powMod(x, n/2, mod);
  t = t * t % mod;
  if (n & 1) return t * x % mod;
  return t;
}

int t(char c) {
  if (c == 'I') return 1;
  if (c == 'V') return 5;
  if (c == 'X') return 10;
  if (c == 'L') return 50;
  if (c == 'C') return 100;
  if (c == 'D') return 500;
  if (c == 'M') return 1000;
  return 0;
}
char it(int n) {
  if (n == 1) return 'I';
  if (n == 5) return 'V';
  if (n == 10) return 'X';
  if (n == 50) return 'L';
  if (n == 100) return 'C';
  if (n == 500) return 'D';
  if (n == 1000) return 'M';
  return 0;
}

int main(void) {
  int n;
  char r[110][110];
  cin >> n;
  rep(i, n) cin >> r[i];

  int num[110][110], d[100] = {};
  rep(i, n) {
    while (r[i][d[i]] != 0) {
      num[i][d[i]] = t(r[i][d[i]]);
      d[i]++;
    }
  }

  int ans = 0;
  rep(i, n) {
    rep(j, d[i] - 1) {
      if (num[i][j] < num[i][j + 1]) ans -= num[i][j];
      else ans += num[i][j];
    }
    ans += num[i][d[i] - 1];
  }
  //cout << ans << endl;

  if (ans > 3999) cout << "ERROR\n";
  else {
    int d = 1000;
    while (d > 0) {
      int j = ans / d;
      if (j < 4) rep(i, j) cout << it(d);
      if (j == 4) cout << it(d) << it(d*5);
      if (5 <= j && j < 9) {
	cout << it(d*5);
	rep(i, j - 5) cout << it(d);
      }
      if (j == 9) cout << it(d) << it(d*10);
      ans %= d; d /= 10;
    }
    cout << endl;
  }
  return 0;
}