#include <bits/stdc++.h>
using namespace std;
int main() {
  char a, b, c, d;
  cin >> a >> b >> c >> d;
  cout << max(abs(a - c), abs(b - d)) << endl;
  while (a != c || b != d) {
    if (a < c) cout << 'R', a++;
    if (a > c) cout << 'L', a--;
    if (b > d) cout << 'D', b--;
    if (b < d) cout << 'U', b++;
    cout << endl;
  }
}
