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<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct Y{
int hx,hy,rx,ry,tim;
};
int c[51][51][51][51];
int main(){
int n,w,h,i,j,a[2]={1,-1},b[2];
Y e;
while(cin>>w>>h&&w!=0&&h!=0){
int mp[52][52]={0};
queue<Y> q;
	cin>>e.hx>>e.hy>>e.rx>>e.ry;
	e.tim=0;
	q.push(e);
	memset(c,0,sizeof(c));
	for(i=0;i<=h+1;i++){
		mp[i][0]=1;
		mp[i][w+1]=1;
	}
	for(i=0;i<=w+1;i++){
		mp[0][i]=1;
		mp[h+1][i]=1;
	}
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
			cin>>mp[j][i];
		}
	}
	while(!q.empty()){
		e=q.front();
		q.pop();
		c[e.hy][e.hx][e.ry][e.rx]=1;
		if(e.tim>=100||e.hx==e.rx&&e.hy==e.ry)break;
		e.tim++;
		for(i=0;i<2;i++){
			if(mp[e.hy+a[i]][e.hx]!=1&&c[e.hy+a[i]][e.hx][e.ry-a[i]][e.rx]==0&&mp[e.ry-a[i]][e.rx]!=1||mp[e.ry-a[i]][e.rx]!=1&&c[e.hy][e.hx][e.ry-a[i]][e.rx]==0&&mp[e.hy+a[i]][e.hx]==1||mp[e.hy+a[i]][e.hx]!=1&&mp[e.ry-a[i]][e.rx]==1&&c[e.hy+a[i]][e.hx][e.ry][e.rx]==0){
				b[0]=0;																										
				b[1]=0;																																		
				if(mp[e.hy+a[i]][e.hx]!=1){																											
					e.hy+=a[i];																																			
					b[0]=1;																																					
				}																																													
				if(mp[e.ry-a[i]][e.rx]!=1){																																										
					e.ry-=a[i];																																		
					b[1]=1;																																																														
				}		
				c[e.hy][e.hx][e.ry][e.rx]=1;																																																																																																																
				q.push(e);																											
				if(b[0]==1)e.hy-=a[i];																														
				if(b[1]==1)e.ry+=a[i];																											
			}																																																												
			if(mp[e.hy][e.hx+a[i]]!=1&&mp[e.ry][e.rx-a[i]]!=1&&c[e.hy][e.hx+a[i]][e.ry][e.rx-a[i]]==0||mp[e.hy][e.hx+a[i]]!=1&&c[e.hy][e.hx+a[i]][e.ry][e.rx]==0&&mp[e.ry][e.rx-a[i]]==1||mp[e.ry][e.rx-a[i]]!=1&&mp[e.hy][e.hx+a[i]]==1&&c[e.hy][e.hx][e.ry][e.rx-a[i]]==0){
				b[0]=0;
				b[1]=0;
				if(mp[e.hy][e.hx+a[i]]!=1){
					e.hx+=a[i];
					b[0]=1;
				}
				if(mp[e.ry][e.rx-a[i]]!=1){
					e.rx-=a[i];
					b[1]=1;
				}
				c[e.hy][e.hx][e.ry][e.rx]=1;
				q.push(e);
				if(b[0]==1)e.hx-=a[i];
				if(b[1]==1)e.rx+=a[i];
			}
		}
		e.tim--;
	}
	if(e.hy==e.ry&&e.hx==e.rx)cout<<e.tim<<endl;
	else cout<<"NA"<<endl;
}
return 0;
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
#include<queue>
#define P pair<int,int>
using namespace std;

bool c[52][52];
int d[52][52];
int x[4] = { -1,0,0,1 }, y[4] = { 0,-1,1,0 };
int main() {
	int a, b;
	while (cin >> a >> b, a | b) {
		memset(c, true, sizeof(c));
		memset(d,-1,sizeof(d));
		int e, f, g, h; cin >> e >> f >> g >> h;
		for (int i = 0; i < b; i++) {
			for (int j = 0; j < a; j++) {
				cin >> c[j + 1][i + 1];
			}
		}
		if (((e + g) & 1) == ((f + h) & 1)) {
		queue<P>Q;
		Q.push(P(e,f));
		d[e][f] = 0;
		while (Q.size()) {
			P o = Q.front(); Q.pop();
			for (int i = 0; i < 4; i++) {
				if (!c[o.first + x[i]][o.second + y[i]]&&!c[e+g-(o.first + x[i])][f+h-(o.second + y[i])]&& d[o.first + x[i]][o.second + y[i]] ==-1) {
					d[o.first + x[i]][o.second + y[i]] = d[o.first][o.second] + 1;
					Q.push(P(o.first + x[i], o.second + y[i]));
				}
			}
		}
		if (d[(e + g) / 2][(f + h) / 2] == -1)puts("NA");
		else cout << d[(e + g) / 2][(f + h) / 2] << endl;
		}
		else puts("NA");
	}
}

C++: #include<bits/stdc++.h>
#define MP make_pair
#define F first
#define S second
using namespace std;
typedef pair<int, int> PII;
typedef pair<PII, PII> PPP;

int x, y;
bool visited[51][51][51][51];
bool flr[52][52];
int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};
int main()
{
  while(true){
    cin >> x >> y;
    if(!x && !y){
      break;
    }

    int tx, ty, kx, ky;
    memset(visited, false, sizeof visited);
    memset(flr, false, sizeof flr);
    cin >> tx >> ty >> kx >> ky;

    for(int i = 1; i <= y; i++){
      for(int j = 1; j <= x; j++){
	int in;
	cin >> in;
	flr[i][j] = (bool)in;
      }
    }

    for(int i = 1; i <= y; i++){
      flr[i][0] = flr[i][x + 1] = true;
    }
    for(int i = 1; i <= x; i++){
      flr[0][i] = flr[y + 1][i] = true;
    }

    queue<PPP> q;
    q.push(MP(MP(ty, tx), MP(ky, kx)));

    for(int i = 0; i <= 100; i++){
      int sz = q.size();
      for(int j = 0; j < sz; j++){
	PPP now = q.front();
	q.pop();
	if(!visited[now.F.F][now.F.S][now.S.F][now.S.S]){
	  visited[now.F.F][now.F.S][now.S.F][now.S.S] = true;
	  
	  if(now.F.F == now.S.F && now.F.S == now.S.S){
	    cout << i << endl;
	    goto end;
	  }
	  
	  for(int k = 0; k < 4; k++){
	    int ntdx = dx[k], ntdy = dy[k], nkdx = -dx[k], nkdy = -dy[k];
	    PPP next = MP(MP(now.F.F + ntdy * !flr[now.F.F + ntdy][now.F.S + ntdx], now.F.S + ntdx * !flr[now.F.F + ntdy][now.F.S + ntdx]), MP(now.S.F + nkdy * !flr[now.S.F + nkdy][now.S.S + nkdx], now.S.S + nkdx * !flr[now.S.F + nkdy][now.S.S + nkdx]));
	    q.push(next);
	  }
	}
      }
    }
    cout << "NA" << endl;
  end:;
  }
  return 0;
}