#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;
#define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;
#define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;}
#define debugaar(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}
#define ALL(v) (v).begin(),(v).end()
#define repeat(l) for(auto cnt=0;cnt<(l);++cnt)
#define iterate(b,e) for(auto cnt=(b);cnt!=(e);++cnt)
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
template<typename T1, typename T2>
ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }

#define TIME chrono::system_clock::now()
#define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count())
namespace {
    std::chrono::system_clock::time_point ttt;
    void tic() { ttt = TIME; }
    void toc() { fprintf(stderr, "TIME : %lldms\n", MILLISEC(TIME - ttt)); }
    std::chrono::system_clock::time_point tle = TIME;
#ifdef __MAI
    void safe_tle(int msec) { assert(MILLISEC(TIME - tle) < msec); }
#else
#define safe_tle(k) ;
#endif
}

#ifdef __MAI
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
#ifdef __VSCC
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#endif
namespace {
#define isvisiablechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T>
        void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        inline MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiablechar(cc); cc = getchar_unlocked());
            for (; isvisiablechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
        }
    };
}
MaiScanner scanner;

template<typename T>
class Field {
public:
    int height, width;
    vector<T> data;
    Field(int h, int w) :height(h), width(w), data(w*h) {}
    inline T& operator()(int y, int x) { return data[x + y*width]; }
    inline T operator()(int y, int x) const { return data[x + y*width]; }
    inline T& at(int y, int x) { return data[x + y*width]; }
    inline T at(int y, int x) const { return data[x + y*width]; }
    inline T safe(int y, int x, int warn) const { return isscreenout(y, x) ? warn : data[x + y*width]; }
    inline bool isscreenout(int y, int x) const { return y<0 || x<0 || height <= y || width <= x; }

    inline bool operator<(const Field& f) const { return data<f.data; }
};

inline bool kadomatu(int a, int b, int c) {
    return a==0||(a<b&&b>c&&a != c) || (a>b&&b<c&&a != c);
}

int height, width;

int main() {

    scanner >> width >> height;

    Field<int> field(height, width);

    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
            scanner >> field(y, x);
        }
    }

    Field<set<int>> dp(height, width);

    queue<vector<int>> q;
    q.push({ 0,field(0,0),0,0,0 });

    while (!q.empty()) {
        int l2 = q.front()[0];
        int l1 = q.front()[1];
        int y = q.front()[2];
        int x = q.front()[3];
        int step = q.front()[4]; q.pop();
        if (y == height - 1 && x == width - 1) {
            cout << step << endl;
            exit(0);
        }
        if (!field.isscreenout(y - 1, x) && kadomatu(l2, l1, field(y - 1, x))) {
            if (dp(y - 1, x).count(field(y, x)) == 0) {
                dp(y - 1, x).insert(field(y, x));
                q.push({ l1,field(y - 1,x),y - 1,x,step + 1 });
            }
        }
        if (!field.isscreenout(y + 1, x) && kadomatu(l2, l1, field(y + 1, x))) {
            if (dp(y + 1, x).count(field(y, x)) == 0) {
                dp(y + 1, x).insert(field(y, x));
                q.push({ l1,field(y + 1,x),y + 1,x,step + 1 });
            }
        }
        if (!field.isscreenout(y, x - 1) && kadomatu(l2, l1, field(y, x - 1))) {
            if (dp(y, x - 1).count(field(y, x)) == 0) {
                dp(y, x - 1).insert(field(y, x));
                q.push({ l1,field(y,x - 1),y,x - 1,step + 1 });
            }
        }
        if (!field.isscreenout(y, x + 1) && kadomatu(l2, l1, field(y, x + 1))) {
            if (dp(y, x + 1).count(field(y, x)) == 0) {
                dp(y, x + 1).insert(field(y, x));
                q.push({ l1,field(y,x + 1),y,x + 1,step + 1 });
            }
        }
    }

    cout << -1 << endl;

    return 0;
}