안전영역

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Sun Oct  2 23:15:51 2022

@author: kimsubin
"""

import sys
input = sys.stdin.readline
sys.setrecursionlimit(100000) #없으면 오류 

def dfs(y, x, a):
    
    dx = [-1, 1, 0, 0]
    dy = [0, 0, -1, 1]
    visited[y][x] = 1
    
    for i in range(4):
        nx, ny = dx[i]+x, dy[i]+y
        if 0<=nx<n and 0<=ny<n and visited[ny][nx]==0 and arr[ny][nx]>a:
            dfs(ny, nx, a)
    
n = int(input())
arr = [list(map(int, input().split())) for _ in range(n)]
List = []
minn = 0
maxn = 0

for i in range(len(arr)):
    
    List.append(max(arr[i]))
    List.append(min(arr[i]))
    
minn = min(List)
maxn = max(List)

ans = 1

for a in range(minn, maxn+1):
    count = 0
    visited = [[0]*n for _ in range(n)]
    for i in range(n):
        for j in range(n):
            if arr[i][j]>a and visited[i][j] == 0:
                dfs(i, j, a)
                count += 1
    if count>ans:
        ans = count

print(ans)