#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  pair<int, int> start, end;
  cin >> s;
  start.first = s[0] - 'a' + 1;
  start.second = s[1] - '0';
  cin >> s;
  end.first = s[0] - 'a' + 1;
  end.second = s[1] - '0';
  vector<string> ans;
  int dem = 0;
  while (start.first < end.first && start.second < end.second) {
    dem++;
    ans.push_back("RU");
    start.first++;
    start.second++;
  }
  while (start.first > end.first && start.second > end.second) {
    dem++;
    ans.push_back("LD");
    start.first--;
    start.second--;
  }
  while (start.first < end.first && start.second > end.second) {
    dem++;
    ans.push_back("RD");
    start.first++;
    start.second--;
  }
  while (start.first > end.first && start.second < end.second) {
    dem++;
    ans.push_back("LU");
    start.first--;
    start.second++;
  }
  while (start.first < end.first) {
    ans.push_back("R");
    dem++;
    start.first++;
  }
  while (start.first > end.first) {
    ans.push_back("L");
    dem++;
    start.first--;
  }
  while (start.second < end.second) {
    ans.push_back("U");
    dem++;
    start.second++;
  }
  while (start.second > end.second) {
    ans.push_back("D");
    dem++;
    start.second--;
  }
  cout << dem << "\n";
  for (int i = 0; i < dem; ++i) cout << ans[i] << "\n";
}
