#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using pll=pair<ll,ll>;
using tll=tuple<ll,ll,ll>;
using ld=long double;
const ll INF=(1ll<<60);
#define rep(i,n) for (ll i=0;i<(ll)(n);i++)
#define all(v) v.begin(),v.end()
template<class T> inline bool chmin(T &a,T b){
    if(a>b){
        a=b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T &a,T b){
    if(a<b){
        a=b;
        return true;
    }
    return false;
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll h,w;
    cin >> h >> w;
    vector<vector<ll>> a(h,vector<ll>(w));
    rep(i,h){
        rep(j,w){
            cin >> a[i][j];
        }
    }
    vector<vector<ll>> c(h,vector<ll>(w,-1));
    vector<ll> pi={0,1,0,-1},pj={1,0,-1,0};
    set<tll> st_0,st_1;
    rep(k,4){
        ll ti=0+pi[k],tj=0+pj[k];
        if(ti<0||h<=ti||tj<0||w<=tj) continue;
        st_0.insert({a[ti][tj],ti,tj});
    }
    c[0][0]=0;

    rep(k,4){
        ll ti=h-1+pi[k],tj=w-1+pj[k];
        if(ti<0||h<=ti||tj<0||w<=tj) continue;
        st_1.insert({a[ti][tj],ti,tj});
    }
    c[h-1][w-1]=1;
    ll x=0,ans=0;
    while(true){
        ans++;
        ll v,si,sj;
        if(x==0){
            tie(v,si,sj)=*begin(st_0);
            c[si][sj]=0;
        }
        if(x==1){
            tie(v,si,sj)=*begin(st_1);
            c[si][sj]=1;
        }
        st_0.erase({v,si,sj});
        st_1.erase({v,si,sj});
        rep(k,4){
            ll ti=si+pi[k],tj=sj+pj[k];
            if(ti<0||h<=ti||tj<0||w<=tj) continue;
            if(c[ti][tj]!=-1&&c[si][sj]==1-c[ti][tj]){
                cout << ans << '\n';
                return 0;
            }
            if(c[ti][tj]!=-1) continue;
            if(x==0) st_0.insert({a[ti][tj],ti,tj});
            if(x==1) st_1.insert({a[ti][tj],ti,tj});
        }
        x++;
        x%=2;
    }
}