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++) {
				if (!d[num.first.first + dx[i]][num.first.second + dy[i]]) {
					copy.first.first = num.first.first + dx[i];
					copy.first.second = num.first.second + dy[i];
				}
				if (!d[num.second.first - dx[i]][num.second.second - dy[i]]) {
					copy.second.first = num.second.first - dx[i];
					copy.second.second = num.second.second - dy[i];
				}
				if (!m[copy]) {
					q.push(copy);
				}
			}
			if (q.empty()) {
				cout << "NA" << endl;
			}
		}
	}
	return 0;
}

C++: #include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define INF (1 << 30)

int xs[] = {0, 1, 0, -1}, ys[] = {1, 0, -1, 0};
int x, y;
int field[55][55];
int dp[55][55][55][55];

int solve(int tx, int ty, int kx, int ky){
  int ntx, nty, nkx, nky;
  if(dp[tx][ty][kx][ky] != -1){
    return dp[tx][ty][kx][ky];
  }
  dp[tx][ty][kx][ky] = INF;
  for(int i = 0;i < 4;i++){
    ntx = tx + xs[i];
    nty = ty + ys[i];
    nkx = kx - xs[i];
    nky = ky - ys[i];
    if(ntx < 0 || ntx >= x || nty < 0 || nty >= y || field[ntx][nty] == 1){
      ntx = tx;
      nty = ty;
    }
    if(nkx < 0 || nkx >= x || nky < 0 || nky >= y || field[nkx][nky] == 1){
      nkx = kx;
      nky = ky;
    }
    dp[tx][ty][kx][ky] = min(dp[tx][ty][kx][ky], solve(ntx, nty, nkx, nky) + 1);
  }
  return dp[tx][ty][kx][ky];
}

int main(){
  int tx, ty, kx, ky;
  while(true){
    scanf("%d%d", &x, &y);
    memset(dp, -1, sizeof(dp));
    if(x == 0 && y == 0) return 0;
    scanf("%d%d", &tx, &ty);
    scanf("%d%d", &kx, &ky);
    for(int i = 0;i < y;i++){
      for(int j = 0;j < x;j++){
	scanf("%d", &field[x][y]);
	dp[i][j][i][j] = 0;
      }
    }
    int ans = solve(tx - 1, ty - 1, kx - 1, ky - 1);
    if(ans > 100)
      puts("NA");
    else
      printf("%d\n", ans);
  }
}

C++: #include<bits/stdc++.h>
using namespace std;
#define fi first
#define sc second
#define pb push_back
typedef pair<int,int> P;
typedef pair<P,P> PP;
typedef pair<int,PP> PPP;
int dx[4]={-1,0,0,1};
int dy[4]={0,-1,1,0};
int S[51][51][51][51];
int S1[51][51][51][51];
int main()
{
	while(true){
		int X,Y;
		int tx;int ty;
		int kx;int ky;
		scanf("%d%d",&X,&Y);
		if(X==0&&Y==0)break;
		scanf("%d%d%d%d",&tx,&ty,&kx,&ky);tx--;ty--;kx--;ky--;
		int grid[51][51];
		for(int i=0;i<Y;i++){
			for(int j=0;j<X;j++){
				scanf("%d",&grid[i][j]);
			}
		}
		
		for(int i=0;i<Y;i++){
			for(int j=0;j<X;j++){
				for(int k=0;k<Y;k++){
					for(int l=0;l<X;l++){
						S[i][j][k][l]=1001;
						S1[i][j][k][l]=1001;
					}
				}
			}
		}
		
		priority_queue<PPP>s;
		PP x;
		x.fi.sc=tx;x.fi.fi=ty;x.sc.sc=kx;x.sc.fi=ky;
		s.push(PPP(0,x));
		int ans=1001;
		while(!s.empty()){
			//printf("%d\n",(int)s.size());
			PPP p=s.top();s.pop();
			if(S[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]<=p.fi)continue;
			
			if(p.sc.fi.fi==p.sc.sc.fi&&p.sc.fi.sc==p.sc.sc.sc){
				ans=min(ans,p.fi);
				
			}
			if(ans<=p.fi+1)continue;
			S[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]=p.fi;
			S1[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]=p.fi;
			if(p.fi==100)continue;
			for(int k=0;k<4;k++){
				PP t;
				if(p.sc.fi.fi+dy[k]<0||p.sc.fi.fi+dy[k]>=Y||p.sc.fi.sc+dx[k]<0||p.sc.fi.sc+dx[k]>=X){
					t.fi.fi=p.sc.fi.fi;t.fi.sc=p.sc.fi.sc;
				}
				else if(grid[p.sc.fi.fi+dy[k]][p.sc.fi.sc+dx[k]]==1){
					t.fi.fi=p.sc.fi.fi;t.fi.sc=p.sc.fi.sc;
				}
				else{
					t.fi.sc=p.sc.fi.sc+dx[k];t.fi.fi=p.sc.fi.fi+dy[k];
				}
				if(p.sc.sc.fi-dy[k]<0||p.sc.sc.fi-dy[k]>=Y||p.sc.sc.sc-dx[k]<0||p.sc.sc.sc-dx[k]>=X){
					t.sc.sc=p.sc.sc.sc;t.sc.fi=p.sc.sc.fi;
				}
				else if(grid[p.sc.sc.fi-dy[k]][p.sc.sc.sc-dx[k]]==1){
					t.sc.sc=p.sc.sc.sc;t.sc.fi=p.sc.sc.fi;
				}
				else{
					t.sc.fi=p.sc.sc.fi-dy[k];t.sc.sc=p.sc.sc.sc-dx[k];
				}
				if(S[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]<=p.fi+1)continue;
				if(S1[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]<=p.fi+1)continue;
				S1[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]=p.fi+1;
				s.push(PPP(p.fi+1,t));
			}
		}
		if(ans==1001)printf("NA\n");
		else printf("%d\n",ans);
		
	}
	return 0;
}