Go: package main

import (
	"container/heap"
	"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 (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)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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)
			}
		}
	}
	fmt.Println("NA")
}

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

C++: #include <iostream>
#include <string>
#include <vector>
#include <cstring>
#include <climits>
#include <algorithm>
#include <map>
using namespace std;

const int dx[] = {-1, 1, 0, 0};
const int dy[] = {0, 0, -1, 1};

int X, Y;
int d[52][52];
int mintime[52][52][52][52];

void dfs(int tx, int ty, int kx, int ky, int t, int &mint) {
    if (tx == kx && ty == ky) {
        mint = min(t, mint);
        return ;
    }
    if (mint <= t) {
        return ;
    }
    mintime[tx][ty][kx][ky] = min(mintime[tx][ty][kx][ky], t);
    for (int i=0; i<4; ++i) {
        if (d[ty+dy[i]][tx+dx[i]] && d[ky-dy[i]][kx-dx[i]]) continue;
        int tx2 = tx, ty2 = ty;
        if ( ! d[ty+dy[i]][tx+dx[i]]) {
            tx2 += dx[i];
            ty2 += dy[i];
        }
        int kx2 = kx, ky2 = ky;
        if ( ! d[ky-dy[i]][kx-dx[i]]) {
            kx2 -= dx[i];
            ky2 -= dy[i];
        }
        if (t+1 < mintime[tx2][ty2][kx2][ky2]) {
            dfs(tx2, ty2, kx2, ky2, t+1, mint);
        }
    }
}

int main() {
    while (cin >> X >> Y, X) {
        int tx, ty, kx, ky;
        cin >> tx >> ty >> kx >> ky;
        for (int i=0; i<=Y+1; ++i) {
            for (int j=0; j<=X+1; ++j) {
                if (i==0 || i==Y+1 || j==0 || j==X+1) d[i][j] = 1;
                else cin >> d[i][j];
            }
        }
        for (int i=1; i<=Y; ++i) for (int j=1; j<=X; ++j) {
            for (int k=1; k<=Y; ++k) for (int l=1; l<=X; ++l) {
                mintime[i][j][k][l] = 101;
            }
        }
        int mint = 101;
        dfs(tx, ty, kx, ky, 0, mint);
        if (mint == 101) {
            cout << "NA" << endl;
        } else {
            cout << mint << endl;
        }
    }
    return 0;
}