#include <iostream>
#include <algorithm>
#include <queue>
#include <tuple>
using namespace std;

                            // N  E  S  W
constexpr array<int, 4> dr = {-1, 0, 1, 0},
                        dc = { 0, 1, 0,-1};
constexpr int dr_size = dr.size();

bool is_kado(int a, int b, int c) {
  if(a == 0) { return true; }
  return a!=c && ((a>b&&b<c) || (a<b&&b>c));
}

int main(void) {
  constexpr int inf = 987654321;
  int C, R; scanf("%d%d", &C, &R);
  vector<vector<int>> G(R, vector<int>(C, 0));
  for(int r=0; r<R; ++r) {
    for(int c=0; c<C; ++c) {
      scanf("%d", &G[r][c]);
    }
  }
  vector<vector<vector<vector<int>>>> cost(R, vector<vector<vector<int>>>(C, vector<vector<int>>(10, vector<int>(10, inf)))); // cost[R][C][10][10]
  cost[0][0][0][G[0][0]] = 0;
  priority_queue<tuple<int, int, int, int, int>, vector<tuple<int, int, int, int, int>>, greater<tuple<int, int, int, int, int>>> pq;
  pq.emplace(0, 0, 0, 0, G[0][0]);
  while(!pq.empty()) {
    int _, r, c, b2, b1; tie(_, r, c, b2, b1) = pq.top(); pq.pop();
    for(int i=0; i<dr_size; ++i) {
      int nr = r + dr[i],
          nc = c + dc[i];
      if(!(0 <= nr && nr < R && 0 <= nc && nc < C)) { continue; }
      if(!is_kado(b2, b1, G[nr][nc])) { continue; }
      if(cost[nr][nc][b1][G[nr][nc]] > cost[r][c][b2][b1] + 1) {
        cost[nr][nc][b1][G[nr][nc]] = cost[r][c][b2][b1] + 1;
        pq.emplace(cost[nr][nc][b1][G[nr][nc]], nr, nc, b1, G[nr][nc]);
      }
    }
  }
  int res = inf;
  for(int b2=0; b2<10; ++b2) {
    for(int b1=0; b1<10; ++b1) {
      res = min(res, cost[R-1][C-1][b2][b1]);
    }
  }
  if(res == inf) { res = -1; }
  printf("%d\n", res);
  return 0;
}