#include <bits/stdc++.h>
using namespace std;
int main() {
  string s1, s2;
  cin >> s1 >> s2;
  int a = s1[0] - s2[0];
  int b = s1[1] - s2[1];
  cout << max(abs(a), abs(b)) << endl;
  while (1) {
    if (s1 == s2) {
      return 0;
    }
    cout << "" << endl;
    int x = s2[0] - s1[0];
    int y = s2[1] - s1[1];
    if (x > 0 && y < 0) {
      cout << "RD";
      s1[0] = s1[0] + 1;
      s1[1] = s1[1] - 1;
      continue;
    }
    if (x == 0 && y > 0) {
      cout << "U";
      s1[1] = s1[1] + 1;
      continue;
    }
    if (x == 0 && y < 0) {
      cout << "D";
      s1[1] = s1[1] - 1;
      continue;
    }
    if (x > 0 && y == 0) {
      cout << "R";
      s1[0] = s1[0] + 1;
      continue;
    }
    if (x < 0 && y == 0) {
      cout << "L";
      s1[0] = s1[0] - 1;
      ;
      continue;
    }
    if (x > 0 && y > 0) {
      cout << "RU";
      s1[0] = s1[0] + 1;
      s1[1] = s1[1] + 1;
      continue;
    }
    if (x < 0 && y > 0) {
      cout << "LU";
      s1[0] = s1[0] - 1;
      s1[1] = s1[1] + 1;
      continue;
    }
    if (x < 0 && y < 0) {
      cout << "LD";
      s1[0] = s1[0] - 1;
      s1[1] = s1[1] - 1;
      continue;
    }
  }
  return 0;
}
