#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=long double;
const ll ILL=2167167167167167167;
const int INF=2100000000;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> int LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> int UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,T b){if(b<a){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
bool yneos(bool a,bool upp=false){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
template<class T> void vec_out(vector<T> &p,int ty=0){
    if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
    else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}
template<class T> T square(T a){return a * a;}

#include <atcoder/modint>
using mint = atcoder::modint998244353;

void solve();
// CITRUS CURIO CITY / FREDERIC
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    rep(i, 0, t) solve();
}

void solve(){
    int H, W;
    cin >> H >> W;
    vector A(H, vector<int>(W));
    rep(i, 0, H) rep(j, 0, W){
        cin >> A[i][j];
    }
    auto f = [&](int sx, int sy) -> vector<vector<int>> {
        vector<int> dx = {1, -1, 0, 0};
        vector<int> dy = {0, 0, 1, -1};
        _pq<pair<int, pair<int, int>>> pq;
        pq.push({A[sx][sy], {sx, sy}});
        int C = 0;
        vector seen(H, vector<int> (W, -1));
        seen[sx][sy] = -2;
        while (!pq.empty()){
            auto tmp = pq.top();
            pq.pop();
            auto [x, y] = tmp.second;
            seen[x][y] = C++;
            rep(k, 0, 4){
                int a = x + dx[k];
                int b = y + dy[k];
                if (a < 0 || b < 0 || H <= a || W <= b) continue;
                if (seen[a][b] != -1) continue;
                seen[a][b] = -2;
                pq.push({A[a][b], {a, b}});
            }
        }
        return seen;
    };
    auto X = f(0, 0);
    auto Y = f(H - 1, W - 1);
    int ans = INF;
    rep(i, 0, H) rep(j, 0, W){
        if (i + 1 != H){
            chmin(ans, max(X[i][j] * 2, Y[i + 1][j] * 2 + 1));
            chmin(ans, max(X[i + 1][j] * 2, Y[i][j] * 2 + 1));
        }
        if (j + 1 != W){
            chmin(ans, max(X[i][j] * 2, Y[i][j + 1] * 2 + 1));
            chmin(ans, max(X[i][j + 1] * 2, Y[i][j] * 2 + 1));
        }
    }
    cout << ans - 1 << "\n";
}