#include<cstdio>
#include<cstring>
struct target
{
	int x,y;
}t[1000001];
struct queue
{
	int x,y;
}q[1000001];
const int mx[4]={0,1,0,-1};
const int my[4]={1,0,-1,0};
int n,m,cnt,x1,y1,x2,y2,head,tail,ans=100000000;
int map[1001][1001];
int dis1[1001][1001];
int dis2[1001][1001];
bool mrk[1001][1001];
inline int min(int a,int b)
{return a<b?a:b;}
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
inline void bfs1(int x,int y)
{
	head=0;tail=1;mrk[x][y]=1;
	q[1].x=x;q[1].y=y;
	while (head<tail)
	{
		int nx=q[++head].x,ny=q[head].y;
		for (int k=0;k<4;k++)
		  {
		  	int xx=nx+mx[k],yy=ny+my[k];
		  	if (xx<1||xx>n||yy<1||yy>m)continue;
		  	if (mrk[xx][yy]||map[xx][yy]==1) continue;
		  	dis1[xx][yy]=dis1[nx][ny]+1;
		  	q[++tail].x=xx;q[tail].y=yy;
		  	mrk[xx][yy]=1;
		  }
	}
}
inline void bfs2(int x,int y)
{
	memset(q,0,sizeof(q));
	memset(mrk,0,sizeof(mrk));
	head=0;tail=1;mrk[x][y]=1;
	q[1].x=x;q[1].y=y;
	while (head<tail)
	{
		int nx=q[++head].x,ny=q[head].y;
		for (int k=0;k<4;k++)
		  {
		  	int xx=nx+mx[k],yy=ny+my[k];
		  	if (xx<1||xx>n||yy<1||yy>m)continue;
		  	if (mrk[xx][yy]||map[xx][yy]==1) continue;
		  	dis2[xx][yy]=dis2[nx][ny]+1;
		  	q[++tail].x=xx;q[tail].y=yy;
		  	mrk[xx][yy]=1;
		  }
	}
}
int main()
{
	m=read();n=read();
	for (int i=1;i<=n;i++)
	  for(int j=1;j<=m;j++)
	  {
	    map[i][j]=read();
	    if (map[i][j]==4)
	    {
	    	t[++cnt].x=i;
	    	t[cnt].y=j;
	    }else
	    if (map[i][j]==2)
	    {
	    	x1=i;
	    	y1=j;
	    	map[i][j]=0;
	    }else
	    if (map[i][j]==3)
	    {
	    	x2=i;
	    	y2=j;
	    	map[i][j]=0;
	    }
	  }
	bfs1(x1,y1);
	bfs2(x2,y2);
	for (int i=1;i<=cnt;i++)
	{
		int nx=t[i].x,ny=t[i].y;
		if (!(dis1[nx][ny]+dis2[nx][ny]))continue;
		ans=min(ans,dis1[nx][ny]+dis2[nx][ny]);
	}
	printf("%d",ans);
	return 0;
}