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

#define CPP_STR(x) CPP_STR_I(x)
#define CPP_CAT(x, y) CPP_CAT_I(x, y)
#define CPP_STR_I(args...) #args
#define CPP_CAT_I(x, y) x##y

#define ASSERT(expr...) assert((expr))

using i8 = int8_t;
using u8 = uint8_t;
using i16 = int16_t;
using u16 = uint16_t;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;

using f32 = float;
using f64 = double;
// }}}

constexpr i64 INF = 1'010'000'000'000'000'017LL;

constexpr i64 MOD = 998244353LL;

constexpr f64 EPS = 1e-12;

constexpr f64 PI = 3.14159265358979323846;

#define M5 100007
#define M9 1000000000

#define F first
#define S second

// util {{{
#define FOR(i, start, end) for (i64 i = (start), CPP_CAT(i, xxxx_end) = (end); i < CPP_CAT(i, xxxx_end); ++i)
#define REP(i, n) FOR(i, 0, n)

#define all(x) (x).begin(), (x).end()
#define ll long long int
#define VI vector<ll>
#define VVI vector<VI>

#define ISD true
#define debug(x) \
    if (ISD)     \
    cout << #x << ": " << x << endl

template <typename T, typename U, typename Comp = less<>>
bool chmax(T &xmax, const U &x, Comp comp = {})
{
    if (comp(xmax, x))
    {
        xmax = x;
        return true;
    }
    return false;
}

template <typename T, typename U, typename Comp = less<>>
bool chmin(T &xmin, const U &x, Comp comp = {})
{
    if (comp(x, xmin))
    {
        xmin = x;
        return true;
    }
    return false;
}

int main()
{
    int H, W;
    cin >> H >> W;
    vector<vector<ll>> A(H, vector<ll>(W));
    REP(i, H)
    REP(j, W)
    cin >> A[i][j];

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

    int x[2], y[2];

    x[1] = 0;
    x[0] = H - 1;
    y[1] = 0;
    y[0] = W - 1;
    using P = pair<int, pair<int, int>>;
    priority_queue<P, vector<P>, greater<P>> q[2];
    q[1].push({0, {0, 0}});
    q[0].push({0, {H - 1, W - 1}});
    set<pair<int, int>> s[2];
    s[1].insert({0, 0});
    s[0].insert({H - 1, W - 1});
    ll ans = 1;
    while (1)
    {
        P t = q[ans % 2].top();
        q[ans % 2].pop();
        int cx = t.S.F;
        int cy = t.S.S;
        if (s[!(ans % 2)].count({cx, cy}) == 1)
        {
            cout << ans - 2 << endl;
            return 0;
        }

        REP(i, 4)
        {
            int nx = cx + dx[i];
            int ny = cy + dy[i];
            if (nx < 0 || nx >= H || ny < 0 || ny >= W || s[ans % 2].count({nx, ny}) == 1)
            {
                continue;
            }
            q[ans % 2].push({A[nx][ny], {nx, ny}});
            s[ans % 2].insert({nx, ny});
        }
        ans++;
    }
}