#3 RE #10 TLE 求调

#include<bits/stdc++.h>
using namespace std;
int n,m,a[1006][1006],ans=INT_MAX;
//int sx1,sy1,sx2,sy2;
bool vis[1006][1006];
const int N=1006;
struct node{
	int x,y,step;
};
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
int sx,sy,sx2[N]={0},sy2[N]={0};
int bfs1(int x,int y,int ex,int ey){
	queue<node> q;
	q.push({x,y,0});
	memset(vis,false,sizeof(vis));
	vis[x][y]=true;
	while(q.size()){
		node dt=q.front();
		q.pop();
		if(dt.x==ex&&dt.y==ey) return dt.step;
		for(int i = 0;i < 4;++i){
			int xx=dt.x+dx[i];
			int yy=dt.y+dy[i];
			if(xx>=1&&xx<=n&&yy>=1&&yy<=m&&!vis[xx][yy]&&a[xx][yy]!=1&&a[xx][yy]!=3){
				q.push({xx,yy,dt.step+1});
				vis[xx][yy]=true;
			}
		}
	}
	return -1;
}
int bfs2(int x,int y){
	queue<node> q;
	q.push({x,y,0});
	memset(vis,false,sizeof(vis));
	vis[x][y]=true;
	while(q.size()){
		node dt=q.front();
		q.pop();
		if(a[dt.x][dt.y]==3) return dt.step;
		for(int i = 0;i < 4;++i){
			int xx=dt.x+dx[i];
			int yy=dt.y+dy[i];
			if(xx>=1&&xx<=n&&yy>=1&&yy<=m&&!vis[xx][yy]&&a[xx][yy]!=1){
			//	cout << xx << " " << yy << "\n";
				q.push({xx,yy,dt.step+1});
				vis[xx][yy]=true;
			}
		}
	}
	return -1;
}
int main(){
	cin>>m>>n;
	int cnt1=0,cnt2=0;
	for(int i = 1;i <= n;++i){
		for(int j = 1;j <= m;++j){
			cin>>a[i][j];
			if(a[i][j]==2){
				sx=i;
				sy=j;
			}
			if(a[i][j]==4){
				sx2[++cnt2]=i;
				sy2[cnt2]=j;
			}
		}
	}
	for(int i = 1;i <= cnt2;++i){
		int l=bfs1(sx,sy,sx2[i],sy2[i]);
		int r=bfs2(sx2[i],sy2[i]);
		if(l==-1||r==-1) continue;
		ans=min(ans,bfs1(sx,sy,sx2[i],sy2[i])+bfs2(sx2[i],sy2[i]));
	}
	cout << ans;
	return 0;
}