#include <bits/stdc++.h>
#define debug(...) ((void)0)
#define postprocess(...) ((void)0)

using namespace std;
using ll = long long;
using ld = long double;

int A[1010][1010];
bool colored[1010][1010];
int color[1010][1010];

int dx[4] = {0, 0, 1, -1};
int dy[4] = {1, -1, 0, 0};

void solve([[maybe_unused]] int test) {
    int H, W;
    cin >> H >> W;

    for (int i = 0; i < H; i++) {
        for (int j = 0; j < W; j++) {
            cin >> A[i][j];
            A[i][j] *= -1;
        }
    }

    colored[0][0] = true;
    colored[H - 1][W - 1] = true;
    color[0][0] = 1;
    color[H - 1][W - 1] = 0;

    priority_queue<pair<int, pair<int, int>>> pque0, pque1;
    pque0.push({A[1][0], {1, 0}});
    pque0.push({A[0][1], {0, 1}});
    pque1.push({A[H - 2][W - 1], {H - 2, W - 1}});
    pque1.push({A[H - 1][W - 2], {H - 1, W - 2}});

    int round = 1;
    while (true) {
        assert(!pque0.empty());

        bool done = false;
        int nx = 0;
        int ny = 0;

        while (!pque0.empty()) {
            auto f = pque0.top();
            pque0.pop();

            auto [x, y] = f.second;
            if (colored[x][y]) {
                continue;
            }

            nx = x;
            ny = y;
            color[nx][ny] = 2 - (round % 2);
            colored[nx][ny] = true;
            done = true;

            for (int k = 0; k < 4; k++) {
                int nx2 = nx + dx[k];
                int ny2 = ny + dy[k];

                if (nx2 < 0 || nx2 >= H || ny2 < 0 || ny2 >= W) {
                    continue;
                }

                pque0.push({A[nx2][ny2], {nx2, ny2}});
            }

            break;
        }

        assert(done);
        bool finished = false;
        for (int k = 0; k < 4; k++) {
            int nx2 = nx + dx[k];
            int ny2 = ny + dy[k];

            if (nx2 < 0 || nx2 >= H || ny2 < 0 || ny2 >= W) {
                continue;
            }

            if ((color[nx][ny] | color[nx2][ny2]) == 3) finished = true;
        }
        if (finished) break;

        round++;
        swap(pque0, pque1);
    }

    cout << round << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    for (int i = 1; i <= t; i++) {
        solve(i);
    }

    postprocess();
}