#include<bits/stdc++.h>
using namespace std;
#define db double
const int N = 1e5+9;
const db eps = 1e-6;
int w,h,sx,sy,ex,ey;
vector<int >v[N];
int hei(db x,db y){
	int a=(int)(x-eps)/2+1;
	int b=(int)(y-eps)/2+1;
	return v[a][b];
}
int main(){
	scanf("%d%d%d%d%d%d",&w,&h,&sy,&sx,&ey,&ex);
	db ans=sqrt((ex-sx)*(ex-sx)+(ey-sy)*(ey-sy));
	for(int i=1;i<=h/2;i++){
		v[i].push_back(0);
		for(int j=1;j<=w/2;j++){
			int x;scanf("%d",&x);v[i].push_back(x);
		}
	}
	for(int i=sx+1;i<=ex-1;i+=2){
		db x=i,y=sy+(db)(i-sx)*(db)(ey-sy)/(db)(ex-sx);
		if(abs((int)(y+0.5)-y)<eps) continue;		
		ans+=abs(hei(x-1,y)-hei(x+1,y));	
	}
	for(int i=sx-1;i>=ex+1;i-=2){
		db x=i,y=sy+(db)(i-sx)*(db)(ey-sy)/(db)(ex-sx);
		if(abs((int)(y+0.5)-y)<eps) continue;		
		ans+=abs(hei(x+1,y)-hei(x-1,y));
	}
	
	for(int i=sy+1;i<=ey-1;i+=2){
		db x=sx+(db)(i-sy)*(db)(ex-sx)/(db)(ey-sy),y=i;
		if(abs((int)(x+0.5)-x)<eps) continue;		
		ans+=abs(hei(x,y-1)-hei(x,y+1));	
	}
	for(int i=sy-1;i>=ey+1;i-=2){
		db x=sx+(db)(i-sy)*(db)(ex-sx)/(db)(ey-sy),y=i;	
		if(abs((int)(x+0.5)-x)<eps) continue;		
		ans+=abs(hei(x,y+1)-hei(x,y-1));	
	}
	
	for(int i=sx+1;i<=ex-1;i+=2){
		db x=i,y=sy+(db)(i-sx)*(db)(ey-sy)/(db)(ex-sx);
		if(abs((int)(y+0.5)-y)<eps){
			int d;
			if(ey>sy) d=1;
			else if(ey==sy) d=0;
			else d=-1;
                        int t=min(hei(x+1,y-d),hei(x-1,y+d));
                        if(t>hei(x-1,y-d)) ans+=abs(t-hei(x-1,y-d))+abs(t-hei(x+1,y+d));
			else ans+=abs(hei(x-1,y-d)-hei(x+1,y+d));
		}		
	}
	for(int i=sx-1;i>=ex+1;i-=2){
		db x=i,y=sy+(db)(i-sx)*(db)(ey-sy)/(db)(ex-sx);
		if(abs((int)(y+0.5)-y)<eps){
			int d;
			if(ey>sy) d=1;
			else if(ey==sy) d=0;
			else d=-1;
                        int t=min(hei(x-1,y-d),hei(x+1,y+d));
			if(t>hei(x+1,y-d)) ans+=abs(hei(x+1,y-d)-t)+abs(t-hei(x-1,y+d));
                        else ans+=abs(hei(x+1,y-d)-hei(x-1,y+d));
		}		
	}
	printf("%.12lf\n",ans);
	return 0;
}
/*

8 8 7 7 1 1
2 3 2 0
2 1 1 2
1 2 0 0
0 0 0 1

*/