#include <bits/stdc++.h>
using namespace std;

int main() {
    int H, W;
    cin >> H >> W;
    vector A(H, vector<int>(W));
    vector<tuple<int, int, int>> cell;
    for( int i = 0; i < H; i++ ) {
        for( int j = 0; j < W; j++ ) {
            cin >> A[i][j];
            cell.push_back(make_tuple(A[i][j], i, j));
        }
    }
    int ans = 0;
    constexpr int INF = 1<<30;
    vector dp(H, vector<int>(W, 1));
    sort(cell.begin(), cell.end());
    for( auto [a, i, j] : cell ) {
        ans = max(ans, dp[i][j]);
        if( i-1 >= 0 && A[i-1][j] > a ) dp[i-1][j] = max(dp[i-1][j], dp[i][j]+1);
        if( i+1 <= H-1 && A[i+1][j] > a ) dp[i+1][j] = max(dp[i+1][j], dp[i][j]+1);
        if( j-1 >= 0 && A[i][j-1] > a ) dp[i][j-1] = max(dp[i][j-1], dp[i][j]+1);
        if( j+1 <= W-1 && A[i][j+1] > a ) dp[i][j+1] = max(dp[i][j+1], dp[i][j]+1);
    }
    cout << ans << endl;
}