#include<cstdio>
#include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#include<vector>
#include<queue>
#include<map>
#include<stack>
#include<set>
using namespace std;
#define maxn 105
typedef pair<pair<int, int>, int> ppii;

const int dx[] = {0, 0, -1, 1};
const int dy[] = {-1, 1, 0, 0};
int r, c, ans, a[maxn][maxn], z;
queue<ppii> q;

struct node {
    int x, y, val;
} w[maxn*maxn];

bool cmp(node a, node b) {
    return a.val > b.val;
}

int bfs(int x, int y) {
    int ret = 1;
    q.push(ppii(make_pair(x, y), 1));
    while(!q.empty()) {
        ppii p = q.front();
        q.pop();
        for(int i = 0; i < 4; ++i) {
            int x = p.first.first, y = p.first.second, cnt = p.second;
            int nx = x+dx[i], ny = y+dy[i];
            if(0 <= nx && nx < r && 0 <= ny && ny < c && a[x][y] > a[nx][ny]) {
                ++cnt;
                ret = max(cnt, ret);
                q.push(ppii(make_pair(nx, ny), cnt));
            }
        }
    }
    return ret;
}

int main() {
    cin >> r >> c;
    for(int i = 0; i < r; ++i) {
        for(int j = 0; j < c; ++j, ++z) {
            scanf("%d", &a[i][j]);
            w[z].val = a[i][j];
            w[z].x = i;
            w[z].y = j;
        }
    }
    sort(w, w+r*c, cmp);
    ans = bfs(w[0].x, w[0].y);
    for(int i = 1; i < r*z; ++i) {
        if(ans >= w[i].val) {
            cout << ans;
            return 0;
        }
        ans = max(bfs(w[i].x, w[i].y), ans);
    }
    cout << ans;
    return 0;
}