Go: package main

import (
	"fmt"
	"math"
)

type Position struct {
	X int64
	Y int64
}

func (one Position) Distance(another Position) int64 {
	return int64(math.Abs(float64(one.X-another.X)) + math.Abs(float64(one.Y-another.Y)))
}

type PersonPosition struct {
	Takayuki Position
	Kazuyuki Position
}

func (one PersonPosition) Distance() int64 {
	return one.Takayuki.Distance(one.Kazuyuki)
}

type Status struct {
	Person PersonPosition
	Turn   int64
}

type PQStatus []*Status

func solve(h, w int64) {
	var tx, ty, kx, ky int64
	fmt.Scan(&tx, &ty, &kx, &ky)
	tx--
	ty--
	kx--
	ky--
	m := make([][]int64, h)
	for i := range m {
		m[i] = make([]int64, w)
		for j := int64(0); j < w; j++ {
			fmt.Scan(&m[i][j])
		}
	}
	start := &Status{Person: PersonPosition{Takayuki: Position{X: tx, Y: ty}, Kazuyuki: Position{X: kx, Y: ky}}, Turn: 0}
	pq := make(PQStatus, 0)
	pq = append(pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(102)
	for len(pq) > 0 {
		now := pq[0]
		pq = pq[1:]
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}

		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = now.Turn

		for i := 0; i < 4; i++ {
			next := &Status{}
			*next = *now
			next.Person.Kazuyuki.X += dx[i]
			next.Person.Kazuyuki.Y += dy[i]
			if next.Person.Kazuyuki.X < 0 || next.Person.Kazuyuki.X >= w ||
				next.Person.Kazuyuki.Y < 0 || next.Person.Kazuyuki.Y >= h ||
				m[next.Person.Kazuyuki.Y][next.Person.Kazuyuki.X] == 1 {
				next.Person.Kazuyuki.X -= dx[i]
				next.Person.Kazuyuki.Y -= dy[i]
			}
			next.Person.Takayuki.X -= dx[i]
			next.Person.Takayuki.Y -= dy[i]
			if next.Person.Takayuki.X < 0 || next.Person.Takayuki.X >= w ||
				next.Person.Takayuki.Y < 0 || next.Person.Takayuki.Y >= h ||
				m[next.Person.Takayuki.Y][next.Person.Takayuki.X] == 1 {
				next.Person.Takayuki.X += dx[i]
				next.Person.Takayuki.Y += dy[i]
			}
			next.Turn++
			if next.Turn <= 100 {
				pq = append(pq, next)
			}
		}
	}
	if ans == 102 {
		fmt.Println("NA")
	} else {
		fmt.Println(ans)
	}
}

func main() {
	var h, w int64
	for {
		fmt.Scan(&h, &w)
		if h == 0 && w == 0 {
			break
		}
		solve(h, w)
	}
}

C++: #include <iostream>
#include <queue>
using namespace std;

int INF=-10;

class point{
    public:
        int x,y;
};

int main(){
    while(1){
        int w,h;
        cin>>w>>h;
        if(w+h==0){
            break;
        }
        int tx,ty;
        int kx,ky;
        cin>>tx>>ty;
        cin>>kx>>ky;

        int d[60][60];
        for(int i=0;i<60;i++){
            for(int j=0;j<60;j++){
                d[i][j]=-1;
            }
        }
        for(int i=1;i<w+1;i++){
            for(int j=1;j<h+1;j++){
                cin>>d[i][j];
                if(d[i][j]==1){
                    d[i][j]=-1;
                }
                if(d[i][j]==0){
                    d[i][j]=INF;
                }
            }
        }

        queue<point> quet;
        queue<point> quek;

        point t;
        t.x=tx; t.y=ty;
        point k;
        k.x=kx; k.y=ky;

        quet.push(t);
        quek.push(k);
        d[t.x][t.y]=0;
        d[k.x][k.y]=0;

        while(!quet.empty()||!quek.empty()){
            t=quet.front(); quet.pop();
            k=quek.front(); quek.pop();

            if(t.x==k.x&&t.y==k.y){
                break;
            }

            if(d[t.x-1][t.y]==INF&&d[k.x+1][k.y]==INF&&d[t.x-1][t.y]!=-1&&d[k.x+1][k.y]!=-1){
                point t2;
                point k2;
                t2.x=t.x-1; t2.y=t.y;
                k2.x=k.x+1; k2.y=k.y;
                quet.push(t2);
                quek.push(k2);
                d[t2.x][t2.y]=d[t.x][t.y]+1;
                d[k2.x][k2.y]=d[k.x][k.y]+1;
            }
            if(d[t.x+1][t.y]==INF&&d[k.x-1][k.y]==INF&&d[t.x+1][t.y]!=-1&&d[k.x-1][k.y]!=-1){
                point t2;
                point k2;
                t2.x=t.x+1; t2.y=t.y;
                k2.x=k.x-1; k2.y=k.y;
                quet.push(t2);
                quek.push(k2);
                d[t2.x][t2.y]=d[t.x][t.y]+1;
                d[k2.x][k2.y]=d[k.x][k.y]+1;
            }
            if(d[t.x][t.y-1]==INF&&d[k.x][k.y+1]==INF&&d[t.x][t.y-1]!=-1&&d[k.x][k.y+1]!=-1){
                point t2;
                point k2;
                t2.x=t.x; t2.y=t.y-1;
                k2.x=k.x; k2.y=k.y+1;
                quet.push(t2);
                quek.push(k2);
                d[t2.x][t2.y]=d[t.x][t.y]+1;
                d[k2.x][k2.y]=d[k.x][k.y]+1;
            }
            if(d[t.x][t.y+1]==INF&&d[k.x][k.y-1]==INF&&d[t.x][t.y+1]!=-1&&d[k.x][k.y-1]!=-1){
                point t2;
                point k2;
                t2.x=t.x; t2.y=t.y+1;
                k2.x=k.x; k2.y=k.y-1;
                quet.push(t2);
                quek.push(k2);
                d[t2.x][t2.y]=d[t.x][t.y]+1;
                d[k2.x][k2.y]=d[k.x][k.y]+1;
            }
        }

        if(t.x==k.x&&t.y==k.y){
            cout<<d[t.x][t.y]<<endl;
        }else{
            cout<<"NA"<<endl;
        }
    }

    return 0;
}

C++: #include <iostream>
#include <sstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
using namespace std;

int main()
{
    int dy[] = {1, 0, -1, 0};
    int dx[] = {0, 1, 0, -1};

    for(;;){
        int w, h;
        cin >> w >> h;
        if(w == 0)
            return 0;

        int tx, ty, kx, ky;
        cin >> tx >> ty >> kx >> ky;

        vector<vector<bool> > grid(h+2, vector<bool>(w+2, true));
        for(int i=1; i<=h; ++i){
            for(int j=1; j<=w; ++j){
                int a;
                cin >> a;
                grid[i][j] = (a == 1);
            }
        }

        vector<vector<int> > minCost((h+2)*(w+2), vector<int>((h+2)*(w+2), INT_MAX));
        minCost[ty*(w+2)+tx][ky*(w+2)+kx] = 0;
        queue<pair<int, int> > q;
        q.push(make_pair(ty*(w+2)+tx, ky*(w+2)+kx));

        bool ok = false;
        while(!q.empty()){
            int a = q.front().first;
            int b = q.front().second;
            int cost = minCost[a][b];
            q.pop();
            if(cost >= 100)
                break;

            int ay0 = a / (w+2);
            int ax0 = a % (w+2);
            int by0 = b / (w+2);
            int bx0 = b % (w+2);
            if(ay0 == by0 && ax0 == bx0){
                cout << cost << endl;
                ok = true;
                break;
            }

            for(int i=0; i<4; ++i){
                int ay = ay0;
                int ax = ax0;
                int by = by0;
                int bx = bx0;
                if(!grid[ay+dy[i]][ax+dx[i]]){
                    ay += dy[i];
                    ax += dx[i];
                }
                if(!grid[by-dy[i]][bx-dx[i]]){
                    by -= dy[i];
                    bx -= dx[i];
                }
                if(cost + 1 < minCost[ay*(w+2)+ax][by*(w+2)+bx]){
                    minCost[ay*(w+2)+ax][by*(w+2)+bx] = cost + 1;
                    q.push(make_pair(ay*(w+2)+ax, by*(w+2)+bx));
                }
            }
        }

        if(!ok)
            cout << "NA" << endl;
    }
}