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 (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 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<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;
typedef pair<int, int>P;
typedef pair<P, P>PP;

int dx[]{ 1,-1,0,0 }, dy[]{ 0,0,1,-1 };
int mp[70][70];
int main() {
	int X, Y;
	while (scanf("%d%d", &X, &Y), X) {
		int tx, ty; scanf("%d%d", &tx, &ty); tx--; ty--;
		int kx, ky; scanf("%d%d", &kx, &ky); kx--; ky--;
		rep(i, Y)rep(j, X)scanf("%d", &mp[j][i]);
		map<PP, int>cnt;
		queue<PP>que;
		cnt[{ {tx, ty}, { kx,ky }}] = 1;
		que.push({ {tx,ty},{kx,ky} });
		while (!que.empty()) {
			PP p = que.front(); que.pop();
			if (p.first == p.second) {
				printf("%d\n", cnt[p] - 1);
				goto goal;
			}
			if (cnt[p] >= 100)continue;
			rep(i, 4) {
				int tnx = p.first.first + dx[i];
				int tny = p.first.second + dy[i];
				int knx = p.second.first - dx[i];
				int kny = p.second.second - dy[i];
				if (tnx < 0 || tnx >= X || tny < 0 || tny >= Y || mp[tnx][tny]) {
					tnx = p.first.first;
					tny = p.first.second;
				}
				if (knx < 0 || knx >= X || kny < 0 || kny >= Y || mp[knx][kny]) {
					knx = p.second.first;
					kny = p.second.second;
				}
				if (!cnt[{ {tnx, tny}, { knx,kny }}]) {
					cnt[{ {tnx, tny}, { knx,kny }}] = cnt[p] + 1;
					que.push({ { tnx, tny },{ knx,kny } });
				}
			}
		}
		puts("NA");
	goal:;
	}
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
using namespace std;
const int INF=1e9;
const int dx[]={1,0,0,-1},dy[]={0,1,-1,0};
int memo[50][50][50][50];
struct data{
    int tx,ty,kx,ky,cnt;
    data(int a,int b,int c,int d,int e)
        :tx(a),ty(b),kx(c),ky(d),cnt(e){}

    data(){}
};
int main(){
    int w,h,tx,ty,kx,ky;
    while(cin>>w>>h,w||h){
        cin>>tx>>ty>>kx>>ky;
        tx--;ty--;kx--;ky--;
        int field[50][50];
        for(int i=0;i<h;i++)
            for(int j=0;j<w;j++)
                cin>>field[i][j];

        fill(memo[0][0][0],memo[0][0][0]+50*50*50*50,INF);

        queue<data>Q;
        Q.push(data(tx,ty,kx,ky,0));
        while(!Q.empty()){
            data d=Q.front();Q.pop();
            if(d.tx<0||d.tx>=w||d.ty<0||d.ty>=h)continue;
            if(d.kx<0||d.kx>=w||d.ky<0||d.ky>=h)continue;
            if(memo[d.tx][d.ty][d.kx][d.ky]<d.cnt)continue;
            if(field[d.ty][d.tx]||field[d.ky][d.kx])continue;
            memo[d.tx][d.ty][d.kx][d.ky]=d.cnt;
            //cout<<d.tx<<" "<<d.ty<<" "<<d.kx<<" "<<d.ky<<" "<<d.cnt<<endl;
            for(int i=0;i<4;i++){
                int ax=d.tx+dx[i],ay=d.ty+dy[i],bx=d.kx+dx[3-i],by=d.ky+dy[3-i];
                if(ax<0||ax>=w||ay<0||ay>=h){
                    ax-=dx[i];ay-=dy[i];
                }
                if(bx<0||bx>=w||by<0||by>=h){
                    bx-=dx[3-i];by-=dy[3-i];
                }
                Q.push(data(ax,ay,bx,by,d.cnt+1));
            }
        }
        int Min=INF;
        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                Min=min(Min,memo[j][i][j][i]);
            }
        }
        if(Min<100)cout<<Min<<endl;
        else cout<<"NA"<<endl;
    }
}

C++: #include<iostream>
#include<utility>
#include<queue>
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];
	bool memo[52][52][52][52];
	while (true) {
		cin >> W >> H;
		if (W == 0)break;
		for (int i = 0; i < 52; i++) {
			for (int j = 0; j < 52; j++) {
				for (int k = 0; k < 52; k++) {
					for (int l = 0; l < 52; l++) {
						memo[i][j][k][l] = false;
					}
				}
			}
		}
		for (int i = 0; i < 52; i++) {
			for (int j = 0; j < 52; 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];
			}
		}
		pair<pair<int, int>, pair<int, int> >num;
		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--;
			memo[num.first.first][num.first.second][num.second.first][num.second.second] = 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++) {
				pair<pair<int, int>, pair<int, int> >copy;
				copy = num;
				copy.first.first += dx[i];
				copy.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 -=dx[i];
				copy.second.second -= dy[i];
				if (d[copy.second.first][copy.second.second]) {
					copy.second.first += dx[i];
					copy.second.second += dy[i];
				}
				if (!memo[copy.first.first][copy.first.second][copy.second.first][copy.second.second]) {
					q.push(copy);
				}
			}
			if (q.empty()) {
				cout << "NA" << endl;
			}
		}
	}
	return 0;
}