#include <bits/stdc++.h>
using namespace std;
#define PB push_back
#define ZERO (1e-10)
#define INF int(1e9+1)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define DEB printf("DEB!\n");
#define D(X) cout<<"  "<<#X": "<<X<<endl;
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
#define IN(n) int n;scanf("%d",&n);
#define FOR(i, m, n) for (int i(m); i < n; i++)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define FT(m, n) FOR(k, m, n)
#define aa first
#define bb second
void ga(int N,int *A){F(N)scanf("%d",A+i);}
struct pt{
    double x,y;
    pt operator-(pt r){return {x-r.x,y-r.y};}
    pt operator+(pt r){return {x+r.x,y+r.y};}
    pt operator*(double a){return {x*a,y*a};}
    double dst(pt r={0,0}){return sqrt((x-r.x)*(x-r.x)+(y-r.y)*(y-r.y));}
    bool gt(){return ~scanf("%lf%lf",&x,&y);}
}B,E,t,q;
struct ln{
    pt a,b;
    void gt(){a.gt(),b.gt();}
};
pt XY(ln a,ln b){
    return {((a.a.x*a.b.y-a.a.y*a.b.x)*(b.a.x-b.b.x)-(a.a.x-a.b.x)
    *(b.a.x*b.b.y-b.a.y*b.b.x))/((a.a.x-a.b.x)*(b.a.y-b.b.y)-(a.a.y-a.b.y)
    *(b.a.x-b.b.x)),((a.a.x*a.b.y-a.a.y*a.b.x)*(b.a.y-b.b.y)-(a.a.y-a.b.y)
    *(b.a.x*b.b.y-b.a.y*b.b.x))/((a.a.x-a.b.x)*(b.a.y-b.b.y)-(a.a.y-a.b.y)*(b.a.x-b.b.x))};
}
#define MVS (1000000)
#define IW(X) EQ((int(X+ZERO)),(X))
pt mv(pt a,pt b,double p){return a+((b-a)*p);}
double S,v[]={.5,-.5};
int W,H,a,l,c;
vector<vi> A,C;
int hg(pt a){if(!c)C[int(a.y)][int(a.x)]=1;return A[int(a.y)][int(a.x)];}
int vg(pt a){return C[int(a.y)][int(a.x)];}
int main(void){
    scanf("%d%d",&W,&H),W/=2,H/=2,B.gt(),E.gt();
    F(H){
        A.PB(vi(0)),C.PB(vi(0));
        FF(W)scanf("%d",&a),A[i].PB(a),C[i].PB(0);
    }
    l=hg(B*.5),S=B.dst(E);
    F(MVS){
        t=mv(B,E,(i+1.)/MVS)*.5;
        if(IW(t.x)||IW(t.y))continue;
        S+=abs(l-hg(t)),l=hg(t);
    }
    if(B.x>E.x)swap(B,E);
    c=1;
    FT(int(B.x),int(E.x))if(!(k&1)){
        t=XY({B,E},{{double(k),0},{double(k),1}})*.5;
        if(!IW(t.y))continue;
        vi u,w;
        F(2)FF(2){
            q={t.x+v[i],t.y+v[j]};
            if(vg(q))u.PB(hg(q));
            else w.PB(hg(q));
        }
        sort(u.begin(),u.end()),sort(w.begin(),w.end());
        if(w[0]>u[1])S+=2*(w[0]-u[1]);
    }
    printf("%.12lf\n",S);
    return 0;
}