#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
istream &operator>>(istream &is, modint &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint &a) { return os << a.val(); }
istream &operator>>(istream &is, modint998244353 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint998244353 &a) { return os << a.val(); }
istream &operator>>(istream &is, modint1000000007 &a) { long long v; is >> v; a = v; return is; }
ostream &operator<<(ostream &os, const modint1000000007 &a) { return os << a.val(); } 

typedef long long ll;
typedef vector<vector<int>> Graph;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define FOR(i,l,r) for (int i = l;i < (int)(r); i++)
#define rep(i,n) for (int i = 0;i < (int)(n); i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define my_sort(x) sort(x.begin(), x.end())
#define my_max(x) *max_element(all(x))
#define my_min(x) *min_element(all(x))
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int INF = (1<<30) - 1;
const ll LINF = (1LL<<62) - 1;
const int MOD = 998244353;
const int MOD2 = 1e9+7;
const double PI = acos(-1);
vector<int> di = {1,0,-1,0};
vector<int> dj = {0,1,0,-1};

#ifdef LOCAL
#  include <debug_print.hpp>
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    int H, W; cin >> H >> W;
    vector A(H, vector<int>(W));
    rep(i,H)rep(j,W) cin >> A[i][j];

    vector color(H, vector<int>(W, -1));
    color[0][0] = 1;
    color[H - 1][W - 1] = 0;

    using P = tuple<int, int, int>; //(val, i, j)
    priority_queue<P, vector<P>, greater<P>> pq1, pq0; 
    rep(d,4){
        int ni = 0 + di[d], nj = 0 + dj[d];
        if(ni < 0 || ni >= H || nj < 0 || nj >= W) continue;
        if(color[ni][nj] != -1) continue;
        pq1.push(P{A[ni][nj], ni, nj});
    }
    rep(d,4){
        int ni = H - 1 + di[d], nj = W - 1 + dj[d];
        if(ni < 0 || ni >= H || nj < 0 || nj >= W) continue;
        if(color[ni][nj] != -1) continue;
        pq0.push(P{A[ni][nj], ni, nj});
    }


    int t = 0;
    bool isFin = false;
    while(true){
        debug(pq1, pq0, color, t);
        if(t % 2 == 0){ // 色1を塗る
            while(true){
                if(pq1.empty()){
                    cout << t << endl;
                    return 0;
                }
                
                auto [val, i, j] = pq1.top();
                pq1.pop();
                if(color[i][j] != -1) continue;

                color[i][j] = 1;
                rep(d,4){
                    int ni = i + di[d], nj = j + dj[d];
                    if(ni < 0 || ni >= H || nj < 0 || nj >= W) continue;
                    if(color[ni][nj] == 0) isFin = true;
                    if(color[ni][nj] != -1) continue;
                    pq1.push(P{A[ni][nj], ni, nj});
                }
                break;
            }
        }
        else{
            while(true){
                if(pq0.empty()){
                    cout << t << endl;
                    return 0;
                }
                
                auto [val, i, j] = pq0.top();
                pq0.pop();
                if(color[i][j] != -1) continue;

                color[i][j] = 0;
                rep(d,4){
                    int ni = i + di[d], nj = j + dj[d];
                    if(ni < 0 || ni >= H || nj < 0 || nj >= W) continue;
                    if(color[ni][nj] == 1) isFin = true;
                    if(color[ni][nj] != -1) continue;
                    pq0.push(P{A[ni][nj], ni, nj});
                }
                break;
            }
        }

        t++;
        if(isFin) break;
    }
    cout << t << endl;
}