Problem:
Score : 300 points

Problem Statement

Dolphin resides in two-dimensional Cartesian plane, with the positive x-axis pointing right and the positive y-axis pointing up.

Currently, he is located at the point (sx,sy). In each second, he can move up, down, left or right by a distance of 1.

Here, both the x- and y-coordinates before and after each movement must be integers.

He will first visit the point (tx,ty) where sx < tx and sy < ty, then go back to the point (sx,sy), then visit the point (tx,ty) again, and lastly go back to the point (sx,sy).

Here, during the whole travel, he is not allowed to pass through the same point more than once, except the points (sx,sy) and (tx,ty).

Under this condition, find a shortest path for him.

Constraints

-1000 ≤ sx < tx ≤ 1000

-1000 ≤ sy < ty ≤ 1000

sx,sy,tx and ty are integers.

Input

The input is given from Standard Input in the following format:

sx sy tx ty

Output

Print a string S that represents a shortest path for Dolphin.

The i-th character in S should correspond to his i-th movement.

The directions of the movements should be indicated by the following characters:

U: Up

D: Down

L: Left

R: Right

If there exist multiple shortest paths under the condition, print any of them.

Sample Input 1

0 0 1 2

Sample Output 1

UURDDLLUUURRDRDDDLLU

One possible shortest path is:

Going from (sx,sy) to (tx,ty) for the first time: (0,0) → (0,1) → (0,2) → (1,2)

Going from (tx,ty) to (sx,sy) for the first time: (1,2) → (1,1) → (1,0) → (0,0)

Going from (sx,sy) to (tx,ty) for the second time: (0,0) → (-1,0) → (-1,1) → (-1,2) → (-1,3) → (0,3) → (1,3) → (1,2)

Going from (tx,ty) to (sx,sy) for the second time: (1,2) → (2,2) → (2,1) → (2,0) → (2,-1) → (1,-1) → (0,-1) → (0,0)

Sample Input 2

-2 -2 1 1

Sample Output 2

UURRURRDDDLLDLLULUUURRURRDDDLLDL

Solution in Ruby (2.3.3) (judge verdict: Wrong Answer)

require 'prime'
include Math
def max(a,b);                           a > b ? a : b                             end
def min(a,b);                           a < b ?  a : b                            end
def swap(a,b);                          a, b = b, a                               end
def gif;                                gets.to_i                                 end
def gi;                                 gets.split.map(&:to_i)                    end
def gs;                                 gets.chomp                                end
def gc;                                 gets.chomp.split('')                      end
def pr(num);                            num.prime_division                        end
def putall(obj);                        obj.each{|o| puts(o)}                     end
def array(size,init = nil);             Array.new(size){init}                     end
def darray(size1, size2, init = nil);   Array.new(size1){Array.new(size2){init}}  end
def rep(num);                           num.times do|i|yield(i) end               end
  def repl(st,en);                      st.upto en-1 do|i|yield(i) end            end

  def culcx x
  	if x > 0
  		"R" * x
  	elsif x < 0
  		"L" * -x
  	end
  end

  def culcy y
  	if y > 0
  		"U" * y
  	elsif y < 0
  		"D" * -y
  	end
  end

  sx,sy,tx,ty = gi
  str = ""
 	x = tx-sx
 	y = ty-sx
 	str += culcy y
 	str += culcx x
 	str += culcy -y
 	str += culcx -x
 	str += culcx -1
 	str += culcy y+1
 	str += culcx x+1
 	str += culcy -1
 	str += culcx 1
 	str += culcy -(y+1)
 	str += culcx -(x+1)
 	str += culcy 1
 	puts str