#include <iostream>
#include <math.h>
#include <vector>
#include <queue>
#include <utility>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;

typedef pair<P, P> PP;

int W, H;

int M[100][100];

int dx[4] = { -1, 0, 1, 0 };
int dy[4] = { 0, 1, 0, -1 };

int d[100][100] = { 0 };

bool isKadomatsu(int a, int b, int c) {
	if (a == 0 || b == 0) return true;

	if ((a == b) || (b == c) || (a == c)) {
		return false;
	}
	else {
		return !(((a < b) && (b < c)) || ((a > b) && (b > c)));
	}
}

int main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);

	cin >> W >> H;

	int k = 0;

	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			cin >> M[i][j];
		}
	}

	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			d[i][j] = -1;
		}
	}
	d[0][0] = 0;

	queue<PP> que;
	que.push(PP(P(0, 0), P(0, 0)));

	
	while (que.size() && k <= 1000000) {
		PP p = que.front(); que.pop();

		int b = M[p.first.first][p.first.second];
		int bb = p.second.second;

		
		for (int i = 0; i < 4; i++) {
			int nx = p.first.first + dx[i];
			int ny = p.first.second + dy[i];


			if (0 <= nx && nx < H && 0 <= ny && ny < W) {
				if (isKadomatsu(bb, b, M[nx][ny])) {
					que.push(PP(P(nx, ny), P(bb, b)));
					d[nx][ny] = d[p.first.first][p.first.second] + 1;
				}
			}
		}
		if (d[H - 1][W - 1] != -1) break;
		k++;

	}
	cout << d[H - 1][W - 1];


    return 0;
}