#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) v.begin(), v.end()

vector<pair<int, int>> dxy = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};

int main() {
    int H, W;
    cin >> H >> W;

    vector<vector<int>> A(H, vector<int>(W));
    vector<vector<int>> visited(H, vector<int>(W, -1));

    vector<priority_queue<vector<int>, vector<vector<int>>, greater<vector<int>>>> hq(2);

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

    visited[0][0] = 0;
    visited[H - 1][W - 1] = 1;

    for (int i = 0; i < 2; ++i) {
        int x = (i == 0) ? 0 : H - 1;
        int y = (i == 0) ? 0 : W - 1;

        for (auto& [dx, dy] : dxy) {
            int _x = x + dx;
            int _y = y + dy;
            if (_x < 0 || _x >= H || _y < 0 || _y >= W) {
                continue;
            }
            hq[i].push({A[_x][_y], _x, _y});
        }
    }

    int i = 0;
    while (true) {
        int ii = i % 2;
        vector<int> tmp = hq[ii].top();
        int a = tmp[0];
        int x = tmp[1];
        int y = tmp[2];
        hq[ii].pop();
        if (visited[x][y] != -1) {
            continue;
        }
        visited[x][y] = ii;

        for (auto& [dx, dy] : dxy) {
            int _x = x + dx;
            int _y = y + dy;
            if (_x < 0 || _x >= H || _y < 0 || _y >= W) {
                continue;
            }
            if (visited[_x][_y] == ii) {
                continue;
            }
            if (visited[_x][_y] == (ii + 1) % 2) {
                cout << i + 1 << endl;
                return 0;
            }
            hq[ii].push({A[_x][_y], _x, _y});
        }
        i++;
    }

    return 0;
}