#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i=0; i<n; i++)
#define debug 0
#define YES cout << "Yes" << endl;
#define NO cout << "No" << endl;
using ll = long long;
using ld = long double;
const int mod = 998244353;
const int MOD = 1000000007;
const double pi = atan2(0, -1);
const int inf = 1 << 31 - 1;
const ll INF = 1LL << 63-1;
#include <time.h>
#include <chrono>

//vectorの中身を空白区切りで出力
template<typename T> 
void print1(vector<T> v) {
	for (int i = 0; i < v.size(); i++) {
		cout << v[i];
		if (i < v.size() - 1) {
			cout << " ";
		}
	}
}

//vectorの中身を改行区切りで出力
template<typename T>
void print2(vector<T> v) {
	for (auto x : v) {
		cout << x << endl;
	}
}

//二次元配列を出力
template<typename T>
void printvv(vector<vector<T>> vv) {
	for (vector<T> v : vv) {
		print1(v);
		cout << endl;
	}
}

//vectorを降順にソート
template<typename T>
void rsort(vector<T> &v) {
	sort(v.begin(), v.end());
	reverse(v.begin(), v.end());
}

//昇順priority_queueを召喚
template<typename T>
struct rpriority_queue {
	priority_queue<T, vector<T>, greater<T>> pq;

	void push(T x) {
		pq.push(x);
	}

	void pop() {
		pq.pop();
	}

	T top() {
		return pq.top();
	}

	size_t size() {
		return pq.size();
	}

	bool empty() {
		return pq.empty();
	}
};

int main() {
	int H ,W;
	cin >> H >> W;
	vector<vector<int>> num(H, vector<int>(W));
	rep(i, H) {
		rep(j, W) {
			cin >> num[i][j];
		}
	}

	vector<vector<int>> col(H, vector<int>(W, -1));
	col[0][0] = 1;
	col[H - 1][W - 1] = 0;
	map<int, vector<int>> mp;
	rep(i, H) {
		rep(j, W) {
			mp[num[i][j]] = { i,j };
		}
	}
	set<int> z, o;
	o.insert(num[1][0]);
	o.insert(num[0][1]);
	z.insert(num[H - 1][W - 2]);
	z.insert(num[H - 2][W - 1]);

	int cnt = 0;
	while (1) {
		bool ed = false;
		if (cnt % 2 == 0) {
			int n = *begin(o);
			int x = mp[n][0];
			int y = mp[n][1];
			col[x][y] = 0;
			if (z.count(n)) {
				ed = true;
			}
			else {
				o.erase(n);
				if (x > 0 && col[x - 1][y] == -1) {
					o.insert(num[x - 1][y]);
				}
				if (x < H - 1 && col[x+1][y]==-1) {
					o.insert(num[x + 1][y]);
				}
				if (y > 0 && col[x][y - 1] == -1) {
					o.insert(num[x][y - 1]);
				}
				if (y < W - 1 && col[x][y + 1] == -1) {
					o.insert(num[x][y + 1]);
				}
			}
		}
		else {
			int n = *begin(z);
			int x = mp[n][0];
			int y = mp[n][1];
			col[x][y] = 1;
			if (o.count(n)) {
				ed = true;
			}
			else {
				z.erase(n);
				if (x > 0 && col[x - 1][y] == -1) {
					z.insert(num[x - 1][y]);
				}
				if (x < H - 1 && col[x + 1][y] == -1) {
					z.insert(num[x + 1][y]);
				}
				if (y > 0 && col[x][y - 1] == -1) {
					z.insert(num[x][y - 1]);
				}
				if (y < W - 1 && col[x][y + 1] == -1) {
					z.insert(num[x][y + 1]);
				}
			}
		}
		cnt++;
		if (ed) {
			break;
		}
	}

	cout << cnt << endl;

}