#define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <math.h>
#include <cmath>
#include <stack>
#include <map>
#include <set>
#include <numeric>
#include <iomanip>
#include <climits>
#include <functional>
#include <cassert>
#include <tuple>
using namespace std;
using ll = long long;

int H, W;
int A[1010][1010];
int dx[4] = {1,0,-1,0};
int dy[4] = {0,1,0,-1};

int main() {

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

    vector vis(H, vector(W, -1));

    // priority_queue<pair<int, pair<int,int>>, 
    //                 vector<pair<int,pair<int,int>>>, 
    //                 greater<pair<int, pair<int,int>>>> pq1,pq0;
    set<pair<int,pair<int,int>>> st1,st0;
    st1.insert({A[0][0], {0,0}});
    st0.insert({A[H-1][W-1], {H-1,W-1}});

    int cnt = -2;
    while(1) {
        cnt++;
        auto [v1, p1] = *st1.begin();
        auto [y1, x1] = p1;
        st1.erase(st1.begin());
        vis[y1][x1] = 1;
        bool f = false;
        for(int i = 0; i < 4; ++i) {
            int nx = x1+dx[i];
            int ny = y1+dy[i];
            if(nx < 0 || nx >= W || ny < 0 || ny >= H) continue;
            if(vis[ny][nx] == 0) {
                f = true;
                break;
            }
            if(vis[ny][nx] == -1) {
                st1.insert({A[ny][nx], {ny,nx}});
            }
        }

        if(f) break;

        cnt++;
        auto [v0, p0] = *st0.begin();
        auto [y0, x0] = p0;
        st0.erase(st0.begin());
        vis[y0][x0] = 0;
        for(int i = 0; i < 4; ++i) {
            int nx = x0+dx[i];
            int ny = y0+dy[i];
            if(nx < 0 || nx >= W || ny < 0 || ny >= H) continue;
            if(vis[ny][nx] == 1) {
                f = true;
                break;
            }
            if(vis[ny][nx] == -1) {
                st0.insert({A[ny][nx], {ny,nx}});
            }
        }

        if(f) break;

    }

    cout << cnt << endl;

    // for(int i = 0; i < H; ++i) {
    //     for(int j = 0; j < W; ++j) cout << vis[i][j] << " ";
    //     cout << endl;
    // }

}