Largest Submatrix 3

### 题目描述 给定一个$n \times m$的正整数矩阵，求其中最大的满足其中不存在两个位置数值相等的子矩阵大小。 ### 输入格式 第一行两个正整数$n , m(1 \leq n , m \leq 400)$表示矩阵的行列数，接下来$n$行每行$m$个正整数$a_i(1 \leq a_i \leq 160000)$描述矩阵。 ### 输出格式 一行一个正整数表示最大子矩阵大小。

You are given matrix $ a $ of size $ n×m $ , its elements are integers. We will assume that the rows of the matrix are numbered from top to bottom from 1 to $ n $ , the columns are numbered from left to right from 1 to $ m $ . We will denote the element on the intersecting of the $ i $ -th row and the $ j $ -th column as $ a_{ij} $ . We'll call submatrix $ i_{1},j_{1},i_{2},j_{2} $ $ (1<=i_{1}<=i_{2}<=n; 1<=j_{1}<=j_{2}<=m) $ such elements $ a_{ij} $ of the given matrix that $ i_{1}<=i<=i_{2} $ AND $ j_{1}<=j<=j_{2} $ . We'll call the area of the submatrix number $ (i_{2}-i_{1}+1)·(j_{2}-j_{1}+1) $ . We'll call a submatrix inhomogeneous, if all its elements are distinct. Find the largest (in area) inhomogenous submatrix of the given matrix.

The first line contains two integers $ n $ , $ m $ ( $ 1<=n,m<=400 $ ) — the number of rows and columns of the matrix, correspondingly. Each of the next $ n $ lines contains $ m $ integers $ a_{ij} $ ( $ 1<=a_{ij}<=160000 $ ) — the elements of the matrix.

Print a single integer — the area of the optimal inhomogenous submatrix.

3 3
1 3 1
4 5 6
2 6 1

6

3 4
5 2 3 1
3 3 5 3
4 4 4 5

4

2 6
1 2 3 4 5 6
8 6 7 8 9 1

8