Codeforces Round 209 (Div. 2)
E
Neatness
Codeforces
2400
原题
← D→
翻译中…

Simon loves neatness. So before he goes to bed, Simon wants to complete all chores in the house.

翻译中…

Simon's house looks like a rectangular table consisting of $*n*$ rows and $*n*$ columns from above. All rows of the table are numbered from $1$ to $*n*$ from top to bottom. All columns of the table are numbered from $1$ to $*n*$ from left to right. Each cell of the table is a room. Pair $(*x*, *y*)$ denotes the room, located at the intersection of the $*x*$-th row and the $*y*$-th column. For each room we know if the light is on or not there.

翻译中…

Initially Simon is in room $(*x*_{0}, *y*_{0})$. He wants to turn off the lights in all the rooms in the house, and then return to room $(*x*_{0}, *y*_{0})$. Suppose that at the current moment Simon is in the room $(*x*, *y*)$. To reach the desired result, he can perform the following steps:

翻译中…
  1. The format of the action is "1". The action is to turn on the light in room $(*x*, *y*)$. Simon cannot do it if the room already has light on.
  2. The format of the action is "2". The action is to turn off the light in room $(*x*, *y*)$. Simon cannot do it if the room already has light off.
  3. The format of the action is "dir" ($*dir*$ is a character). The action is to move to a side-adjacent room in direction $*dir*$. The direction can be left, right, up or down (the corresponding dir is L, R, U or D). Additionally, Simon can move only if he see a light in the direction $*dir*$. More formally, if we represent the room, Simon wants to go, as $(*nx*, *ny*)$, there shold be an integer $*k*$ $(*k* > 0)$, that room $(*x* + (*nx* - *x*)*k*, *y* + (*ny* - *y*)*k*)$ has a light. Of course, Simon cannot move out of his house.
翻译中…

Help Simon, find the sequence of actions that lets him achieve the desired result.

翻译中…

Input

翻译中…

The first line contains three positive integers $*n*, *x*_{0}, *y*_{0}$ $(2 ≤ *n* ≤ 500, 1 ≤ *x*_{0}, *y*_{0} ≤ *n*)$.

翻译中…

Next $*n*$ lines contain the description of rooms in the house. The $*i*$-th line contains $*n*$ space-separated integers $*a*_{*i*1}, *a*_{*i*2}, ..., *a*_{*in*}$. If number $*a*_{*ij*}$ equals zero, then room $(*i*, *j*)$ has light off, and if number $*a*_{*ij*}$ equals one, then room $(*i*, *j*)$ has light on. It is guaranteed that at least one room has light on.

翻译中…

Output

翻译中…

If there is no desired sequence of actions, print "NO" (without the quotes). Otherwise, print "YES" (without the quotes) and the description of the required sequence of actions as a string. Note that you do not have to minimize the length of the sequence of actions but you shouldn't use more than $3·10^{6}$ actions.

翻译中…

样例

Input #1
3 1 1
1 0 0
0 1 0
1 0 0
Output #1
YES
D1R2L2D2UU2
InputCopy OutputCopy
Input #2
3 1 1
1 0 0
0 1 0
0 0 1
Output #2
NO
InputCopy OutputCopy
题目信息
题号
359E
时间限制
2 s
内存限制
256 MB
标签
构造
DFS 及类似

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。