#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef double ld;

struct Pt{ ld x,y,z; };

ld dist(Pt a, Pt b){
    Pt c={b.x-a.x,b.y-a.y,b.z-a.z};
    return sqrt(c.x*c.x+c.y*c.y+c.z*c.z);
}

vector<vector<ll>> a;

ll closest_height(ld x, ld y){
    ll xx=(int)floor(x);
    ll yy=(int)floor(y);
    /* cerr<<xx<<' '<<yy<<endl; */
    return a[yy/2][xx/2];
}

int main(){
    ll W,H,Sx,Sy,Ex,Ey;
    cin>>W>>H>>Sx>>Sy>>Ex>>Ey;
    --Sx;--Sy;--Ex;--Ey;
    a=vector<vector<ll>>(H/2,vector<ll>(W/2));
    for(auto &v:a)for(ll &i:v)cin>>i;
    ld x=Sx;
    ld y=Sy;
    ld dx=Ex-Sx;
    ld dy=Ey-Sy;
    ld step=1e-7;
    Pt last;
    Pt cur={x,y,(ld)closest_height(x,y)};
    ld res=0;
    for(ld ratio=0;ratio<1;ratio+=step){
        last=cur;
        x=Sx+ratio*dx;
        y=Sy+ratio*dy;
        cur={x,y,(ld)closest_height(x,y)};
        /* if(cur.z != last.z){ */
        /*     cerr<<"z: "<<cur.x<<' '<<cur.y<<' '<<cur.z<<endl; */
        /* } */
        res += dist(cur,last);
    }
    cout << fixed << setprecision(12);
    cout << res << endl;
    return 0;
}