4723: Vanya and Balloons

内存限制:256 MB 时间限制:2 S
题面:传统 评测方式:文本比较 上传者:
提交:1 通过:1

题目描述

time limit per test
3 seconds
memory limit per test
512 megabytes
input
standard input
output
standard output
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:

**o**
**o**
ooooo
**o**
**o**
or

o***o
*o*o*
**o**
*o*o*
o***o
Formally, the cross is given by three integers r, c and d, such that dr,cn-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|<d. Rotated cross consists of balloons located in cells (x,y), such that |x-r|=|y-c| and |x-r|<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 109+7.
Input
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.
Output
Print the maximum possible product modulo 109+7. Note, that you are not asked to maximize the remainder modulo 109+7, but to find the maximum value and print it this modulo.
Examples
Input
4
1233
0213
2020
0303
Output
108
Input
5
00300
00300
33333
00300
00300
Output
19683
Input
5
00003
02030
00300
03020
30000
Output
108
Input
5
21312
10003
10002
10003
23231
Output
3
Input
5
12131
12111
12112
21311
21212
Output
24
Note
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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