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A10416. Vanya and Balloons

编程题 普及/提高-

题目描述

Vanya plays a game of balloons on the field of size $n×n$ , where each cell contains a balloon with one of the values $0$ , $1$ , $2$ or $3$ . The goal is to destroy a cross, such that the product of all values of balloons in the cross is maximum possible. There are two types of crosses: normal and rotated. For example:

<br></br>**o**<br></br>**o**<br></br>ooooo<br></br>**o**<br></br>**o**<br></br>or

<br></br>o***o<br></br>*o*o*<br></br>**o**<br></br>*o*o*<br></br>o***o<br></br>Formally, the cross is given by three integers $r$ , $c$ and $d$ , such that $d<=r,c<=n-d+1$ . The normal cross consists of balloons located in cells $(x,y)$ (where $x$ stay for the number of the row and $y$ for the number of the column), such that $|x-r|·|y-c|=0$ and $|x-r|+|y-c|&lt;d$ . Rotated cross consists of balloons located in cells $(x,y)$ , such that $|x-r|=|y-c|$ and $|x-r|&lt;d$ .

Vanya wants to know the maximum possible product of the values of balls forming one cross. As this value can be large, output it modulo $10^{9}+7$ .

输入格式

The first line of the input contains a single integer $n$ ( $1<=n<=1000$ ) — the number of rows and columns in the table with balloons.

The each of the following $n$ lines contains $n$ characters '0', '1', '2' or '3' — the description of the values in balloons.

输出格式

Print the maximum possible product modulo $10^{9}+7$ . Note, that you are not asked to maximize the remainder modulo $10^{9}+7$ , but to find the maximum value and print it this modulo.

输入输出样例

输入 #1
4
1233
0213
2020
0303
输出 #1
108
输入 #2
5
00300
00300
33333
00300
00300
输出 #2
19683
输入 #3
5
00003
02030
00300
03020
30000
输出 #3
108
输入 #4
5
21312
10003
10002
10003
23231
输出 #4
3
输入 #5
5
12131
12111
12112
21311
21212
输出 #5
24

说明/提示

In the first sample, the maximum product is achieved for a rotated cross with a center in the cell $(3,3)$ and radius $1$ : $2·2·3·3·3=108$ .
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