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 Java7 (OpenJDK 1.7.0) (judge verdict: Accepted)

import java.io.*;
import java.util.*;
class Main
{
    static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	static FastScanner sc=new FastScanner(br);
    static PrintWriter out=new PrintWriter(System.out);
	static Random rnd=new Random();
	
    public static void main(String args[]) throws Exception
    {
		int sx=sc.nextInt(),sy=sc.nextInt(),tx=sc.nextInt(),ty=sc.nextInt();
		int uc=0,rc=0,sx1=sx,sy1=sy;List<Character> list=new ArrayList<Character>();
		while(sy1<ty)
		{
			list.add('U');uc++;sy1++;
		}
		while(sx1<tx)
		{
			list.add('R');rc++;sx1++;
		}
		int tx1=tx,ty1=ty;int dc=0;
		while(ty1>sy)
		{
			list.add('D');dc++;ty1--;
		}
		while(tx1>sx)
		{
			list.add('L');tx1--;
		}
		int curr_x=sx;curr_x--;int curr_y=sy+uc+1;sx1=sx;sy1=sy;
		while(sx1>curr_x)
		{
			list.add('L');sx1--;
		}
		while(sy1<curr_y)
		{
			list.add('U');sy1++;
		}
		while(curr_x<tx)
		{
			list.add('R');curr_x++;
		}
		while(curr_y>ty)
		{
			list.add('D');curr_y--;
		}
		curr_x=tx+1;
		while(tx<curr_x)
		{
			list.add('R');tx++;
		}
		curr_y=ty-dc-1;
		while(ty>curr_y)
		{
			list.add('D');ty--;
		}
		while(curr_x>sx)
		{
			list.add('L');curr_x--;
		}
		while(curr_y<sy)
		{
			list.add('U');curr_y++;
		}
		for(char ch:list)
		{
			out.print(ch);
		}
		out.println("");out.close();
    }
}
class Pair
{
	int x,y;
	public Pair(int x,int y)
	{
		this.x=x;this.y=y;
	}
}
class FastScanner
{
    BufferedReader in;
    StringTokenizer st;

    public FastScanner(BufferedReader in) {
        this.in = in;
    }
	
    public String nextToken() throws Exception {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }
	
	public String next() throws Exception {
		return nextToken().toString();
	}
	
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() throws Exception {
        return Long.parseLong(nextToken());
    }

    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }
}