#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int H,W; cin >> H >> W;
    vector<vector<int>> A(H,vector<int>(W));
    for(auto &h : A) for(auto &w : h) cin >> w;

    vector dist(H,vector(W,vector(100,-1)));
    queue<tuple<int,int,int>> Q; 
    dist.at(0).at(0).at(0) = 0,Q.push({0,0,0});
    vector<pair<int,int>> dxy = {{-1,0},{0,1},{1,0},{0,-1}};
    while(Q.size()){
        auto [x,y,V] = Q.front(); Q.pop();
        int a0 = V/10,a1 = V%10;
        for(auto [dx,dy] : dxy){
            int nx = x+dx,ny = y+dy;
            if(nx < 0 || ny < 0 || nx >= H || ny >= W) continue;
            int a2 = A.at(nx).at(ny);
            if(dist.at(nx).at(ny).at(a1*10+a2) != -1) continue;
            if(a1 == a2 || a0 == a2) continue;
            if(a0 != 0 && a0 < a1 && a1 < a2) continue;
            if(a0 != 0 && a0 > a1 && a1 > a2) continue;
            dist.at(nx).at(ny).at(a1*10+a2) = dist.at(x).at(y).at(V)+1,Q.push({nx,ny,a1*10+a2});
        }
    }

    int answer = 1001001001;
    for(int i=0; i<100; i++) if(dist.at(H-1).at(W-1).at(i) != -1) answer = min(answer,dist.at(H-1).at(W-1).at(i));
    if(answer > 1e9) answer = -1;
    cout << answer << endl;
}