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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int h, w;
    cin >> h >> w;
    vector<vector<int>> A(h, vector<int>(w)), B(h, vector<int>(w, -1));
    for(auto &&vec : A){
        for(auto &&v : vec) cin >> v;
    }
    A[0][0] = A[h - 1][w - 1] = 1;
    priority_queue<tuple<int,int,int>, vector<tuple<int,int,int>>, greater<tuple<int,int,int>>> pq1, pq2;
    pq1.emplace(0, 0, 0);
    pq2.emplace(0, h - 1, w - 1);
    B[0][0] = 0;
    B[h - 1][w - 1] = 1;
    for(int i = 0; i < h * w; i++){
        int s = i % 2;
        auto [v, y, x] = (s == 0 ? pq1.top() : pq2.top());
        (s == 0 ? pq1.pop() : pq2.pop());
        B[y][x] = s;
        for(int j = 0; j < 4; j++){
            int ny = y + (j == 0) - (j == 1);
            int nx = x + (j == 2) - (j == 3);
            if(ny < 0 || nx < 0 || ny >= h || nx >= w) continue;
            if(B[ny][nx] >= 0 && B[ny][nx] != s){
                cout << i + 1 - 2 << '\n';
                return 0;
            }
            if((-B[ny][nx] - 1) >> s & 1) continue;
            B[ny][nx] -= 1 << s;
            if(s == 0){
                pq1.emplace(A[ny][nx], ny, nx);
            }else{
                pq2.emplace(A[ny][nx], ny, nx);
            }
        }
    }
}