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

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)

#define ll long long
#define ull unsigned ll

void reader(int *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(ll *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
int reader(char c[]){int i,s=0;for(;;){mygc(i);if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF) break;}c[s++]=i;for(;;){mygc(i);if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF) break;c[s++]=i;}c[s]='\0';return s;}
template <class T, class S> void reader(T *x, S *y){reader(x);reader(y);}
template <class T, class S, class U> void reader(T *x, S *y, U *z){reader(x);reader(y);reader(z);}
template <class T, class S, class U, class V> void reader(T *x, S *y, U *z, V *w){reader(x);reader(y);reader(z);reader(w);}

void writer(int x, char c){int s=0,m=0;char f[10];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(ll x, char c){int s=0,m=0;char f[20];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(const char c[]){int i;for(i=0;c[i]!='\0';i++)mypc(c[i]);}
void writer(const char x[], char c){int i;for(i=0;x[i]!='\0';i++)mypc(x[i]);mypc(c);}
template<class T> void writerLn(T x){writer(x,'\n');}
template<class T, class S> void writerLn(T x, S y){writer(x,' ');writer(y,'\n');}
template<class T, class S, class U> void writerLn(T x, S y, U z){writer(x,' ');writer(y,' ');writer(z,'\n');}
template<class T> void writerArr(T x[], int n){int i;if(!n){mypc('\n');return;}rep(i,n-1)writer(x[i],' ');writer(x[n-1],'\n');}

#define MD 1000000007

int X, Y;
int M[111][111];

int q[2222222], q_st, q_size;
int dist[2222222];

int isK(int a, int b , int c){
  if(!a || !b || !c) return 1;
  if(a==c) return 0;
  if(a < b && b > c) return 1;
  if(a > b && b < c) return 1;
  return 0;
}

void coordinate_compress2(int mode, int &mask, int &a, int &b){
  static int B;
  if(mode==-1){
    B = b;
  } else if(mode==0){
    a = mask / B;
    b = mask % B;
  } else {
    mask = a * B + b;
  }
}

struct coordinate_compress2 {
  int B;
  void set(int b){
    B = b;
  }
  void set(int a, int b){
    B = b;
  }
  int mask(int a, int b){
    return a * B + b;
  }
  void para(int mask, int *a, int *b){
    *a = mask / B;
    *b = mask % B;
  }
};


struct coordinate_compress3 {
  int B, C;
  void set(int b, int c){
    B = b;
    C = c;
  }
  void set(int a, int b, int c){
    B = b;
    C = c;
  }
  int mask(int a, int b, int c){
    return (a * B + b) * C + c;
  }
  void para(int mask, int *a, int *b, int *c){
    *a = mask / (B*C);
    *b = mask % (B*C) / C;
    *c = mask % C;
  }
};


struct coordinate_compress4 {
  int B, C, D;
  void set(int b, int c, int d){
    B = b;
    C = c;
    D = d;
  }
  void set(int a, int b, int c, int d){
    B = b;
    C = c;
    D = d;
  }
  int mask(int a, int b, int c, int d){
    return ((a * B + b) * C + c) * D + d;
  }
  void para(int mask, int *a, int *b, int *c, int *d){
    *a = mask / (B*C*D);
    *b = mask % (B*C*D) / (C*D);
    *c = mask % (C*D) / D;
    *d = mask % D;
  }
};


int main(){
  int i, j, k, a, b, d;
  int mask, nmask;
  int res = -1;
  int dx[4] = {-1,1,0,0}, dy[4] = {0,0,-1,1};
  int ni, nj;
  coordinate_compress3 coo;

  reader(&Y,&X);
  rep(i,X) rep(j,Y) reader(M[i]+j);

  coo.set(10, X, Y);

  rep(i,10*X*Y) dist[i] = -1;
  dist[0] = 0;
  q_st = q_size = 0;
  q[q_st+q_size++] = 0;

  while(q_size){
    mask = q[q_st++]; q_size--;
    coo.para(mask, &k, &i, &j);

    if(i==X-1 && j==Y-1){
      res = dist[mask];
      break;
    }

    rep(d,4){
      ni = i + dx[d];
      nj = j + dy[d];
      if(ni < 0 || nj < 0 || ni >= X || nj >= Y) continue;
      if(!isK(k,M[i][j],M[ni][nj])) continue;

      nmask = coo.mask(M[i][j], ni, nj);
      if(dist[nmask] >= 0) continue;
      dist[nmask] = dist[mask] + 1;
      q[q_st+q_size++] = nmask;
    }
  }

  writerLn(res);

  return 0;
}