#include <bits/stdc++.h>
#define INF 1000000001LL
#define LNF 1000000000000000001LL
#define MOD 998244353LL
#define MAX 1005
#define long long long
#define all(x) x.begin(),x.end()
using namespace std;

int main()
{
	ios_base::sync_with_stdio(0); 
    cin.tie(0);
    int n,m;
    cin >> n >> m;

    int pan[n][m];

    for(int i = 0; i<n; i++)
    {
        for(int j = 0;j<m; j++)
            cin >> pan[i][j];
    }

    int dx[4] = {-1,0,0,1};
    int dy[4] = {0,-1,1,0};
    int vis[n][m];
    memset(vis,0,sizeof vis);

    priority_queue<pair<int,pair<int,int>>> pqA; 
    priority_queue<pair<int,pair<int,int>>> pqB;
    pqA.push({pan[0][0],{0,0}});
    pqB.push({pan[n-1][m-1],{n-1,m-1}});
    int cnt = -2;
    while(true)
    {
        pair<int,int> x = pqA.top().second;
        pqA.pop();
        while(vis[x.first][x.second])
        {
            x = pqA.top().second;
            pqA.pop();
        }
        vis[x.first][x.second] = 1;
        cnt++;
        for(int i = 0; i<4; i++)
        {
            int xx = x.first+dx[i];
            int yy = x.second+dy[i];

            if(xx < 0 || yy < 0 || xx>=n || yy >=m)
                continue;
            if(vis[xx][yy] == 2)
            {
                cout << cnt << endl;
                return 0;
            }
            if(vis[xx][yy])
                continue;
            pqA.push({-pan[xx][yy],{xx,yy}});
        }
        x = pqB.top().second;
        pqB.pop();

        while(vis[x.first][x.second])
        {
            x = pqB.top().second;
            pqB.pop();
        }
        vis[x.first][x.second] = 2;
        cnt++;
        for(int i = 0; i<4; i++)
        {
            int xx = x.first+dx[i];
            int yy = x.second+dy[i];

            if(xx < 0 || yy < 0 || xx>=n || yy >=m)
                continue;
            if(vis[xx][yy] == 1)
            {
                cout << cnt << endl;
                return 0;
            }
            if(vis[xx][yy])
                continue;
            pqB.push({-pan[xx][yy],{xx,yy}});
        }
    }

    return 0;
}