#include <bits/stdc++.h>
using namespace std;
const int max_n = 104;
int n, ret, a[max_n][max_n], e[max_n][max_n], h = 1;
bool visited[max_n][max_n];
int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, 1, 0, -1};

void dfs(int y, int x) {
    visited[y][x] = 1;
    for (int i=0; i<4; ++i) {
        int ny = y + dy[i];
        int nx = x + dx[i];
        if (ny < 0 || ny >= n || nx < 0 || nx >= n) continue;
        if (e[ny][nx] == 0 && !visited[ny][nx]) dfs(ny, nx);
    }
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); 
    
    cin >> n;
    for (int i=0; i<n; ++i) {
        for (int j=0; j<n; ++j) {
            cin >> a[i][j];
        }
    }
    
    while (h <= 100) {
        fill(&visited[0][0], &visited[0][0] + max_n * max_n, 0);
        int temp = 0;
        for (int i=0; i<n; ++i) {
            for (int j=0; j<n; ++j) {
                if (e[i][j] == 1) continue;
                if (a[i][j] <= h) e[i][j] = 1;
            }
        }
        
        for (int i=0; i<n; ++i) {
            for (int j=0; j<n; ++j) {
                if (e[i][j] == 0 && !visited[i][j]) {
                    dfs(i, j);
                    ++temp;
                }
            }
        }
        ret = max(ret, temp);
        ++h;
    }
    
    cout << ret << "\n";
    
    return 0;
}