import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;


public class Main {
  public static void main(String[] args) {
    FastScanner sc = new FastScanner();
    int N = sc.nextInt();

    int total = 0;
    for (int i = 0; i < N; i++) {
      total += r2i(sc.next());
    }

    if (total <= 3999) {
      System.out.println(i2r(total));
    } else {
      System.out.println("ERROR");
    }
  }

  private static String i2r(int n) {
    StringBuilder sb = new StringBuilder();
    while (n >= 1000) {
      sb.append("M");
      n -= 1000;
    }
    if (n >= 900) {
      sb.append("CM");
      n -= 900;
    }
    if (n >= 500) {
      sb.append("D");
      n -= 500;
    }
    if (n >= 400) {
      sb.append("CD");
      n -= 400;
    }

    while (n >= 100) {
      sb.append("C");
      n -= 100;
    }

    if (n >= 90) {
      sb.append("XC");
      n -= 90;
    }
    if (n >= 50) {
      sb.append("L");
      n -= 50;
    }
    if (n >= 40) {
      sb.append("XL");
      n -= 40;
    }
    while (n >= 10) {
      sb.append("X");
      n -= 10;
    }
    if (n >= 9) {
      sb.append("IX");
      n -= 9;
    }
    if (n >= 5) {
      sb.append("V");
      n -= 5;
    }
    if (n >= 4) {
      sb.append("IV");
      n -= 4;
    }
    while (n >= 1) {
      sb.append("I");
      n -= 1;
    }
    return sb.toString();
  }

  private static int r2i(String s) {
    int ret = 0;
    for (int i = 0; i < s.length(); i++) {
      int c1 = s.charAt(i);
      boolean flg = false;
      if (i < s.length() - 1) {
        int c2 = s.charAt(i + 1);

        if (c1 == 'I') {
          if (c2 == 'X') {
            ret += 9;
            flg = true;
          } else if (c2 == 'V') {
            ret += 4;
            flg = true;
          }
        } else if (c1 == 'X') {
          if (c2 == 'L') {
            ret += 40;
            flg = true;
          } else if (c2 == 'C') {
            ret += 90;
            flg = true;
          }
        } else if (c1 == 'C') {
          if (c2 == 'D') {
            ret += 400;
            flg = true;
          } else if (c2 == 'M') {
            ret += 900;
            flg = true;
          }
        }
      }
      if (flg) {
        i++;
      } else if (c1 == 'I') {
        ret += 1;
      } else if (c1 == 'V') {
        ret += 5;
      } else if (c1 == 'X') {
        ret += 10;
      } else if (c1 == 'L') {
        ret += 50;
      } else if (c1 == 'C') {
        ret += 100;
      } else if (c1 == 'D') {
        ret += 500;
      } else if (c1 == 'M') {
        ret += 1000;
      }
    }
    return ret;
  }
}


class FastScanner {
  public static String debug = null;

  private final InputStream in = System.in;
  private int ptr = 0;
  private int buflen = 0;
  private byte[] buffer = new byte[1024];
  private boolean eos = false;

  private boolean hasNextByte() {
    if (ptr < buflen) {
      return true;
    } else {
      ptr = 0;
      try {
        if (debug != null) {
          buflen = debug.length();
          buffer = debug.getBytes();
          debug = "";
          eos = true;
        } else {
          buflen = in.read(buffer);
        }
      } catch (IOException e) {
        e.printStackTrace();
      }
      if (buflen < 0) {
        eos = true;
        return false;
      } else if (buflen == 0) {
        return false;
      }
    }
    return true;
  }

  private int readByte() {
    if (hasNextByte())
      return buffer[ptr++];
    else
      return -1;
  }

  private static boolean isPrintableChar(int c) {
    return 33 <= c && c <= 126;
  }

  private void skipUnprintable() {
    while (hasNextByte() && !isPrintableChar(buffer[ptr]))
      ptr++;
  }

  public boolean isEOS() {
    return this.eos;
  }

  public boolean hasNext() {
    skipUnprintable();
    return hasNextByte();
  }

  public String next() {
    if (!hasNext())
      throw new NoSuchElementException();
    StringBuilder sb = new StringBuilder();
    int b = readByte();
    while (isPrintableChar(b)) {
      sb.appendCodePoint(b);
      b = readByte();
    }
    return sb.toString();
  }

  public long nextLong() {
    if (!hasNext())
      throw new NoSuchElementException();
    long n = 0;
    boolean minus = false;
    int b = readByte();
    if (b == '-') {
      minus = true;
      b = readByte();
    }
    if (b < '0' || '9' < b) {
      throw new NumberFormatException();
    }
    while (true) {
      if ('0' <= b && b <= '9') {
        n *= 10;
        n += b - '0';
      } else if (b == -1 || !isPrintableChar(b)) {
        return minus ? -n : n;
      } else {
        throw new NumberFormatException();
      }
      b = readByte();
    }
  }

  public int nextInt() {
    return (int) nextLong();
  }

  public long[] nextLongList(int n) {
    return nextLongTable(1, n)[0];
  }

  public int[] nextIntList(int n) {
    return nextIntTable(1, n)[0];
  }

  public long[][] nextLongTable(int n, int m) {
    long[][] ret = new long[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        ret[i][j] = nextLong();
      }
    }
    return ret;
  }

  public int[][] nextIntTable(int n, int m) {
    int[][] ret = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        ret[i][j] = nextInt();
      }
    }
    return ret;
  }
}