#pragma region template
#include<bits/stdc++.h>
using namespace std;
#include <atcoder/modint>
using namespace atcoder;
using mint=modint998244353;
template<class T>inline bool chmax(T &a,T b){if(a<b){a=b;return true;}return false;}
template<class T>inline bool chmin(T &a,T b){if(a>b){a=b;return true;}return false;}
#define rep1(i,a) for(int i=0;i<(int)(a);i++)
#define rep2(i,a,b) for(int i =(int)(a);i<(int)(b);i++)
#define rep3(i,a,b,c) for(int i=(int)(a);i<(int)(b);i+=(int)(c))
#define overloadRep(a,b,c,d,e,...)e
#define rep(...) overloadRep(__VA_ARGS__,rep3,rep2,rep1)(__VA_ARGS__)
#define rrep(i,a,b) for(int i=(int)(a);i<=(int)(b);i++)
#define drep(i,a,b) for(int i=(int)(a);i>=(int)(b);i--)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define spa " "
#define yes "Yes"
#define no "No"
#define int long long
const int inf=8e18;
const int dx[4]={0,1,0,-1};
const int dy[4]={1,0,-1,0};
using P=pair<int,int>;
using T=tuple<int,int,int>;
bool bit(int &x,int &p){return (x>>p)&1;}

#pragma endregion

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout<<fixed<<setprecision(15);

    int h,w;cin>>h>>w;
    vector<vector<int>>a(h,vector<int>(w));rep(i,h)rep(j,w)cin>>a[i][j];
    vector<vector<int>>col(h,vector<int>(w,-1));
    col[0][0]=0;col[h-1][w-1]=1;

    int now=false;
    set<T>st0,st1;
    vector used0(h,vector<bool>(w));
    vector used1(h,vector<bool>(w));
    st0.emplace(a[0][1],0,1);used0[0][1]=true;
    st0.emplace(a[1][0],1,0);used0[1][0]=true;
    st1.emplace(a[h-1][w-2],h-1,w-2);used1[h-1][w-2]=true;
    st1.emplace(a[h-2][w-1],h-2,w-1);used1[h-2][w-1]=true;

    int ans=0;

    while(true){
        ans++;
        if(!now){
            auto[val,i,j]=*st0.begin();
            //cout<<i<<spa<<j<<spa<<now<<spa<<a[i][j]<<endl;
            st0.erase(st0.begin());
            col[i][j]=now;
            rep(d,4){
                int ni=i+dx[d],nj=j+dy[d];
                if(ni<0 or ni>=h or nj<0 or nj>=w)continue;
                if(col[ni][nj]==now)continue;
                if(col[ni][nj]==1){cout<<ans<<endl;return 0;}
                if(used0[ni][nj])continue;
                st0.emplace(a[ni][nj],ni,nj);
                used0[ni][nj]=true;
            }
        }else{
            auto[val,i,j]=*st1.begin();
            //cout<<i<<spa<<j<<spa<<now<<spa<<a[i][j]<<endl;            
            st1.erase(st1.begin());
            col[i][j]=now;
            rep(d,4){
                int ni=i+dx[d],nj=j+dy[d];
                if(ni<0 or ni>=h or nj<0 or nj>=w)continue;
                if(col[ni][nj]==now)continue;
                if(col[ni][nj]==0){cout<<ans<<endl;return 0;}
                if(used1[ni][nj])continue;
                st1.emplace(a[ni][nj],ni,nj);
                used1[ni][nj]=true;
            }            
        }
        now^=1;
    }
    return 0;
}