Codeforces Round 188 (Div. 1)
E
Princess and Her Shadow
Codeforces
3100
原题
← D→
翻译中…

Princess Vlada enjoys springing in the meadows and walking in the forest. One day — wonderful, sunny day — during her walk Princess found out with astonishment that her shadow was missing! "Blimey!", — she thought and started her search of the shadow in the forest.

翻译中…

Normally the Shadow is too lazy and simply sleeps under the Princess. But at this terrifically hot summer day she got bored of such a dull life, so she decided to play with Vlada.

翻译中…

The forest, where our characters entertain themselves, may be represented as a set of integer cells in the plane, where the Shadow and the Princess can move only up, down, left and right by $1$. Some cells (as it happens in decent forests) are occupied by trees. The Shadow and the Princess are not allowed to enter a cell occupied by a tree. Unfortunately, these are the hard times for the forest, so there are very few trees growing here...

翻译中…

At first the Princess was walking within the cell ($*v*_{*x*}$, $*v*_{*y*}$), while the Shadow hid from the Princess in the cell ($*s*_{*x*}$, $*s*_{*y*}$). The Princess, The Shadow and the trees are located in the different cells.

翻译中…

The Shadow is playing with the Princess. As soon as the Princess moves by $1$ in some direction, the Shadow simultaneously flies by $1$ in the same direction, if it is possible (if the cell to fly to is not occupied by some tree); otherwise, the Shadow doesn't move. The Shadow is very shadowy, so our characters do not interfere with each other.

翻译中…

We say that the Shadow is caught by the Princess if after some move both of them are located in the same cell. Vlada managed to catch her Shadow! Can you?

翻译中…

Input

翻译中…

First line of the input contains the coordinates of the characters $*v*_{*x*}$, $*v*_{*y*}$, $*s*_{*x*}$, $*s*_{*y*}$ and the number of trees $*m*$ ($0 ≤ *m* ≤ 400$). The following $*m*$ lines contain the coordinates of the trees.

翻译中…

All the coordinates are integers between -100 and 100, inclusive. The Princess, The Shadow and the trees are located in the different cells.

翻译中…

Output

翻译中…

If it is impossible for the Princess to catch the Shadow, print "-1" (without quotes).

翻译中…

Otherwise print a sequence of characters "L", "R", "D", "U", corresponding to the Princess's moves, following which she will be able to catch the Shadow at some turn (L — move to the left, R — to the right, U — up, D — down; axis $*x*$ is directed to the right, $*y*$ — up).

翻译中…

The number of characters (that is, the number of moves) must not exceed $10^{6}$. All the Princess's moves should be correct, that is must not lead to the cell where a tree grows. It is allowed for the Princess and the Shadow to occupy the same cell before the last turn.

翻译中…

Note

翻译中…

Below the pictures for the samples are given (Princess, Shadow and the trees are colored in pink, gray and black correspondingly; the blue dot marks the lattice center).

翻译中…

In the first case the Princess may make two left steps, one step upwards and one right step: image

翻译中…

In the following case the Princess cannot catch the Shadow: image

翻译中…

In the last sample the Princess may make two left steps and one down step (in any order): image

翻译中…

样例

Input #1
0 0 1 0 1
0 1
Output #1
LLUR
InputCopy OutputCopy
Input #2
5 0 3 0 8
2 -1
2 0
2 1
3 -1
4 1
4 0
3 1
4 -1
Output #2
-1
InputCopy OutputCopy
Input #3
3 2 1 1 3
0 1
1 0
0 0
Output #3
DLL
InputCopy OutputCopy
题目信息
题号
317E
时间限制
1 s
内存限制
256 MB
标签
构造
最短路

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。