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 := &Status{}
		*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<utility>
#include<queue>
#include<map>
using namespace std;
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
int main() {
	int W, H, tx, ty, kx, ky;
	bool d[52][52];
	map<pair<pair<int, int>, pair<int, int> >,bool> m;
	pair<pair<int, int>, pair<int, int> >num;
	pair<pair<int, int>, pair<int, int> >copy;
	while (true) {
		cin >> W >> H;
		if (W == 0)break;
		for (int i = 0; i < H+2; i++) {
			for (int j = 0; j < W+2; j++) {
				d[i][j] = 1;
			}
		}
		cin >> tx >> ty >> kx >> ky;
		for (int i = 1; i < H + 1; i++) {
			for (int j = 1; j < W + 1; j++) {
				cin >> d[j][i];
			}
		}
		num.first.first = tx;
		num.first.second = ty;
		num.second.first = kx;
		num.second.second = ky;
		queue<pair<pair<int, int>, pair<int, int> > > q;
		q.push(num);
		int qsize = q.size();
		int loopcount = 0;
		while (!q.empty()) {
			num = q.front();
			q.pop();
			if (qsize == 0) {
				qsize = q.size()+1;
				loopcount++;
				if (loopcount == 100) {
					cout << "NA" << endl;
					break;
				}
			}
			qsize--;
			m[num] = true;
			swap(num.first, num.second);
			m[num] = true;
			if (num.first.first == num.second.first && num.first.second == num.second.second) {
				cout << loopcount << endl;
				break;
			}
			for (int i = 0; i < 4; i++) {
				copy.first.first = num.first.first+dx[i];
				copy.first.second = num.first.second+dy[i];
				if (d[copy.first.first][copy.first.second]) {
					copy.first.first -= dx[i];
					copy.first.second -= dy[i];
				}
				copy.second.first =num.second.first-dx[i];
				copy.second.second =num.second.second- dy[i];
				if (d[copy.second.first][copy.second.second]) {
					copy.second.first += dx[i];
					copy.second.second += dy[i];
				}
				if (!m[copy]) {
					q.push(copy);
				}
			}
			if (q.empty()) {
				cout << "NA" << endl;
			}
		}
	}
	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <cstring>
#include <cctype>
#include <sstream>
#include <set>
#include <map>
#include <queue>
#include <complex>
using namespace std;

int main() {
	int X, Y;
	while(cin >> X >> Y, X|Y) {
		bool b = true;
		int tx, ty, kx, ky, map[Y][X];
		cin >> tx >> ty >> kx >> ky;
		for(int i=0; i<Y; i++)
			for(int j=0; j<X; j++)
				cin >> map[i][j];

		queue<int> q;
		set<int> memo;

		q.push(0);
		q.push((tx-1)*1000000+(ty-1)*10000+(kx-1)*100+ky-1);

		while(q.size()) {
			int tx2, ty2, kx2, ky2, chk, cnt;
			cnt = q.front();
			q.pop();
			tx = q.front() /1000000;
			ty = q.front() /10000 %100;
			kx = q.front() /100 %100;
			ky = q.front() %100;

			if(tx == kx && ty == ky) {
				b = false;
				cout << cnt << endl;
				break;
			}
			if(cnt>99) {
				cout << "NA" << endl;
				break;
			}
			if(ty>0 && !map[ty-1][tx]) {
				ty--;
				if(ky<Y-1 && !map[ky+1][kx])
					ky++;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				ty = q.front() /10000 %100;
				ky = q.front() %100;
			}
			if(tx>0 && !map[ty][tx-1]) {
				tx--;
				if(kx<X-1 && !map[ky][kx+1])
					kx++;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				tx = q.front() /1000000;
				kx = q.front() /100 %100;
			}
			if(ty>Y-1 && !map[ty+1][tx]) {
				ty++;
				if(ky>0 && !map[ky-1][kx])
					ky--;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				ty = q.front() /10000 %100;
				ky = q.front() %100;
			}
			if(tx<X-1 && !map[ty][tx+1]) {
				tx++;
				if(kx>0 && !map[ky][kx-1])
					kx--;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				tx = q.front() /1000000;
				kx = q.front() /100 %100;
			}

			if(ky>0 && !map[ky-1][kx]) {
				ky--;
				if(ty<Y-1 && !map[ty+1][tx])
					ty++;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				ty = q.front() /10000 %100;
				ky = q.front() %100;
			}
			if(kx>0 && !map[ky][kx-1]) {
				kx--;
				if(tx<X-1 && !map[ty][tx+1])
					tx++;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				tx = q.front() /1000000;
				kx = q.front() /100 %100;
			}
			if(ky>Y-1 && !map[ky+1][kx]) {
				ky++;
				if(ty>0 && !map[ty-1][tx])
					ty--;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				ty = q.front() /10000 %100;
				ky = q.front() %100;
			}
			if(kx<X-1 && !map[ky][kx+1]) {
				kx++;
				if(tx>0 && !map[ty][tx-1])
					tx--;
				chk = tx*1000000+ty*10000+kx*100+ky;
				if(memo.find(chk) == memo.end()) {
					memo.insert(chk);
					q.push(cnt+1);
					q.push(chk);
				}
				tx = q.front() /1000000;
				kx = q.front() /100 %100;
			}
			q.pop();
		}
		if(b) cout << "NA" << endl;
	}
	return 0;
}