#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (int i = (s); i < (int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (int i = (int)(s - 1); i >= (int)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
T chmax(T& a, const U& b) {
    if (a >= b) return false;
    a = b;
    return true;
}
template <typename T, typename U>
T chmin(T& a, const U& b) {
    if (a <= b) return false;
    a = b;
    return true;
}

void yes_no(bool f, string yes = "Yes", string no = "No") { cout << (f ? yes : no) << "\n"; }

void solve() {
    int w, h;
    cin >> w >> h;
    vector<vi> s(h, vi(w));
    rep(i, h) rep(j, w) cin >> s[i][j];
    int dx[] = {0, -1, 0, 1};
    int dy[] = {-1, 0, 1, 0};
    auto isOutOfRange = [](int h, int w, int H, int W) {
        return h < 0 || h >= H || w < 0 || w >= W;
    };
    using T = tuple<int, int, int>;
    const int inf = 1e9;
    const int ma = 11;
    vector d(h, vector(w, vector(ma, inf)));
    priority_queue<T> q;
    rep(i, ma) if (s[0][0] != i) {
        d[0][0][i] = 0;
        q.emplace(0, 0, i);
    }
    auto iskad = [](int i, int j, int k) {
        if (i == j || j == k || k == i) return false;
        vi v{i, j, k};
        sort(all(v));
        return i == v[1] || k == v[1];
    };
    while (!q.empty()) {
        auto [y, x, pre] = q.top();
        q.pop();
        int cur = s[y][x];
        // cout << y << " " << x << " " << pre << " " << cur << '\n';
        rep(i, 4) {
            int nx = x + dx[i], ny = y + dy[i];
            if (isOutOfRange(ny, nx, h, w)) continue;
            int nxt = s[ny][nx];
            if (iskad(pre, cur, nxt) && chmin(d[ny][nx][cur], d[y][x][pre] + 1)) {
                q.emplace(ny, nx, cur);
            }
        }
    }
    int ans = *min_element(all(d[h - 1][w - 1]));
    if (ans == inf) ans = -1;
    cout << ans << "\n";
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    // multi-testcase
    // cin >> t;
    rep(ti, t) solve();
    return 0;
}