#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
typedef long long ll;
typedef long double ld;
#define int ll
#define OVERLOAD_REP(_1, _2, _3, name, ...) name
#define REP2(i, l, r) for (int i = (int)(l); i < (int)(r); i++)
#define REP1(i, n) REP2(i, 0, n)
#define rep(...) OVERLOAD_REP(__VA_ARGS__, REP2, REP1)(__VA_ARGS__)
#define RREP2(i, l, r) for (int i = (int)(l)-1; i >= (int)(r); i--)
#define RREP1(i, n) RREP2(i, n, 0)
#define rrep(...) OVERLOAD_REP(__VA_ARGS__, RREP2, RREP1)(__VA_ARGS__)
#define all(...) begin(__VA_ARGS__), end(__VA_ARGS__)
#define rall(...) rbegin(__VA_ARGS__), rend(__VA_ARGS__)
#define debug(x) cerr << #x << ": " << (x) << endl
#define pb push_back
#define mp make_pair
#define mt make_tuple
const int INF = 4e18;
const int MOD = 1e9 + 7;
const int MOD2 = 998244353;
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; }
template<class... T> void input(T&... args) { ((cin >> args), ...); }
template<class... T> void print(T... args) { ((cout << args << " "), ...); }
template<class... T> void println(T... args) { print(args...); cout << endl; }

signed main() {
	int H, W;
	input(H, W);
	vector<vector<int>> A(H, vector<int>(W));
	rep(i, H) rep(j, W) input(A[i][j]);
	vector<vector<int>> B(H, vector<int>(W, -1));
	B[0][0] = 1;
	B[H-1][W-1] = 0;
	
	priority_queue<
		pair<int, pair<int, int>>,
        vector<pair<int, pair<int, int>>>,
        greater<pair<int, pair<int, int>>>
    > color0_next;
    color0_next.push(mp(A[H-2][W-1], mp(H-2, W-1)));
    color0_next.push(mp(A[H-1][W-2], mp(H-1, W-2)));
    
	priority_queue<
		pair<int, pair<int, int>>,
        vector<pair<int, pair<int, int>>>,
        greater<pair<int, pair<int, int>>>
    > color1_next;
    color1_next.push(mp(A[1][0], mp(1, 0)));
    color1_next.push(mp(A[0][1], mp(0, 1)));
    
	int i = 1;
	while (true) {
		if (i % 2 == 0) {
			while (!color0_next.empty()) {
				auto [di, dj] = color0_next.top().second;
				color0_next.pop();
				if (B[di][dj] == -1) {
					B[di][dj] = 0;
					for (auto [ddi, ddj] : {mp(-1, 0), mp(0, -1), mp(1, 0), mp(0, 1)}) {
						ddi = max(0LL, min(H-1, di + ddi));
						ddj = max(0LL, min(W-1, dj + ddj));
						if (B[ddi][ddj] == 1) {
							println(i);
							return 0;
						} else if (B[ddi][ddj] == -1) {
							color0_next.push(mp(A[ddi][ddj], mp(ddi, ddj)));
						}
					}
					break;
				}
			}
		} else {
			while (!color1_next.empty()) {
				auto [di, dj] = color1_next.top().second;
				color1_next.pop();
				if (B[di][dj] == -1) {
					B[di][dj] = 1;
					for (auto [ddi, ddj] : {mp(-1, 0), mp(0, -1), mp(1, 0), mp(0, 1)}) {
						ddi = max(0LL, min(H-1, di + ddi));
						ddj = max(0LL, min(W-1, dj + ddj));
						if (B[ddi][ddj] == 0) {
							println(i);
							return 0;
						} else if (B[ddi][ddj] == -1) {
							color1_next.push(mp(A[ddi][ddj], mp(ddi, ddj)));
						}
					}
					break;
				}
			}
		}
		++i;
	}
}