Go: package main

import (
	"fmt"
	"math"
	"container/heap"
)

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 (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

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)
	heap.Init(&pq)
	heap.Push(&pq, start)
	//pq.Push(start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(101)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		//now := pq.Pop().(*Status)
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}
		if v, ok := memo[now.Person]; ok && v <= now.Turn {
			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 += 1
			if next.Turn < 100 {
				heap.Push(&pq, next)
				//pq.Push(next)
			}
		}
	}
	if ans == 101 {
		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 <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;
    }
}

C++: #include<bits/stdc++.h>

using namespace std;

struct Data
{
    int tx, ty, kx, ky, cost;
    Data() {}
    Data(int _tx, int _ty, int _kx, int _ky, int _cost)
    {
        tx = _tx;
        ty = _ty;
        kx = _kx;
        ky = _ky;
        cost = _cost;
    }
};

const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int W, H, fld[50][50];
bool isUsed[50][50][50][50];

bool IsAbleToMove(int x, int y)
{
    return x < 0 || W <= x || y < 0 || H <= y || fld[y][x] == 1;
}

int main()
{
    while (cin >> W >> H, W || H)
    {
        int tx, ty, kx, ky;
        cin >> tx >> ty >> kx >> ky;
        tx--; ty--; kx--; ky--;
        for (int i = 0; i < H; i++)
        {
            for (int j = 0; j < W; j++)
            {
                cin >> fld[i][j];
            }
        }

        queue<Data> q;
        q.push(Data(tx, ty, kx, ky, 0));
        Data qf;
        fill_n((bool*)isUsed, 50 * 50 * 50 * 50, false);
        while (!q.empty() && q.front().cost < 100)
        {
            qf = q.front();
            q.pop();
            if (qf.tx == qf.kx && qf.ty == qf.ky)
            {
                printf("%d\n", qf.cost);
                goto END_OF_DATASET;
            }
            if (isUsed[qf.tx][qf.ty][qf.kx][qf.ky]) continue;
            isUsed[qf.tx][qf.ty][qf.kx][qf.ky] = true;
            for (int i = 0; i < 4; i++)
            {
                int ntx = qf.tx + dx[i], nty = qf.ty + dy[i];
                int nkx = qf.kx + dx[(i + 2) % 4], nky = qf.ky + dy[(i + 2) % 4];
                if (IsAbleToMove(ntx, nty))
                {
                    ntx = qf.tx;
                    nty = qf.ty;
                }
                if (IsAbleToMove(nkx, nky))
                {
                    nkx = qf.kx;
                    nky = qf.ky;
                }
                q.push(Data(ntx, nty, nkx, nky, qf.cost + 1));
            }
        }
        puts("NA");
        END_OF_DATASET:;
    }
    return 0;
}