This documentation is automatically generated by online-judge-tools/verification-helper
// verification-helper: PROBLEM https://yukicoder.me/problems/222
#include<bits/stdc++.h>
using namespace std;
#define call_from_test
#include "../../tools/iskado.cpp"
#undef call_from_test
signed main(){
cin.tie(0);
ios::sync_with_stdio(0);
int w,h;
cin>>w>>h;
vector<vector<int>> st(h,vector<int>(w));
for(int i=0;i<h;i++)
for(int j=0;j<w;j++)
cin>>st[i][j];
using T = tuple<int, int, int, int>;
map<T, int> dp;
queue<T> qu;
if(st[0][0]!=st[0][1]){
dp[T(0,0,0,1)]=1;
qu.emplace(0,0,0,1);
}
if(st[0][0]!=st[1][0]){
dp[T(0,0,1,0)]=1;
qu.emplace(0,0,1,0);
}
int dy[]={0,0,1,-1};
int dx[]={1,-1,0,0};
auto in=[&](int y,int x){return 0<=y&&y<h&&0<=x&&x<w;};
int ans=-1;
while(!qu.empty()){
int py,px,cy,cx;
tie(py,px,cy,cx)=qu.front();qu.pop();
if(cy==h-1&&cx==w-1){
ans=dp[T(py,px,cy,cx)];
break;
}
for(int k=0;k<4;k++){
int ny=cy+dy[k],nx=cx+dx[k];
if(!in(ny,nx)) continue;
if(!is_kado(st[py][px],st[cy][cx],st[ny][nx])) continue;
if(dp.count(T(cy,cx,ny,nx))) continue;
dp[T(cy,cx,ny,nx)]=dp[T(py,px,cy,cx)]+1;
qu.emplace(cy,cx,ny,nx);
}
}
cout<<ans<<endl;
return 0;
}
#line 1 "test/yukicoder/0222.test.cpp"
// verification-helper: PROBLEM https://yukicoder.me/problems/222
#include<bits/stdc++.h>
using namespace std;
#define call_from_test
#line 1 "tools/iskado.cpp"
#line 3 "tools/iskado.cpp"
using namespace std;
#endif
//BEGIN CUT HERE
template<typename T>
bool is_kado(T a,T b,T c){
if(a==b or b==c or c==a) return 0;
if(a<b and b>c) return 1;
if(a>b and b<c) return 1;
return 0;
}
//END CUT HERE
#ifndef call_from_test
//INSERT ABOVE HERE
signed main(){
return 0;
}
#endif
#line 8 "test/yukicoder/0222.test.cpp"
#undef call_from_test
signed main(){
cin.tie(0);
ios::sync_with_stdio(0);
int w,h;
cin>>w>>h;
vector<vector<int>> st(h,vector<int>(w));
for(int i=0;i<h;i++)
for(int j=0;j<w;j++)
cin>>st[i][j];
using T = tuple<int, int, int, int>;
map<T, int> dp;
queue<T> qu;
if(st[0][0]!=st[0][1]){
dp[T(0,0,0,1)]=1;
qu.emplace(0,0,0,1);
}
if(st[0][0]!=st[1][0]){
dp[T(0,0,1,0)]=1;
qu.emplace(0,0,1,0);
}
int dy[]={0,0,1,-1};
int dx[]={1,-1,0,0};
auto in=[&](int y,int x){return 0<=y&&y<h&&0<=x&&x<w;};
int ans=-1;
while(!qu.empty()){
int py,px,cy,cx;
tie(py,px,cy,cx)=qu.front();qu.pop();
if(cy==h-1&&cx==w-1){
ans=dp[T(py,px,cy,cx)];
break;
}
for(int k=0;k<4;k++){
int ny=cy+dy[k],nx=cx+dx[k];
if(!in(ny,nx)) continue;
if(!is_kado(st[py][px],st[cy][cx],st[ny][nx])) continue;
if(dp.count(T(cy,cx,ny,nx))) continue;
dp[T(cy,cx,ny,nx)]=dp[T(py,px,cy,cx)]+1;
qu.emplace(cy,cx,ny,nx);
}
}
cout<<ans<<endl;
return 0;
}