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 <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <string>
#include <algorithm>
#include <utility>
#include <vector>
#include <list>
#include <deque>
#include <stack>
#include <queue>
#include <map>
#include <set>
#define INF (2000000000)
#define MOD (1000000007)
using namespace std;

typedef vector<int> VI;
typedef vector<int>::iterator VII;
typedef vector<double> VD;
typedef vector<double>::iterator VDI;
typedef pair<int, int> P;


typedef struct
{
	int tx, ty, kx, ky;
} POS;

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

bool maze[100][100];
int X, Y;
POS f;
int d[52][52][52][52];

int search()
{
	queue<POS> que;
	
	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++){
					d[i][j][k][l] = INF;
				}
			}
		}
	}
	
	que.push(f);
	d[f.tx][f.ty][f.kx][f.ky] = 0;
	
	while (que.size()){
		POS now = que.front();
		que.pop();
		
		//printf("%d %d %d %d\n", now.tx, now.ty, now.kx, now.ky);
		
		if (now.tx == now.kx && now.ty == now.ky){
			return (d[now.tx][now.ty][now.kx][now.ky]);
		}
		
		for (int i = 0; i < 4; i++){
			POS to;
			if (maze[now.tx + dx[i]][now.ty + dy[i]] || maze[now.kx - dx[i]][now.ky - dy[i]]){
				continue;
			}
			else {
				to.tx = now.tx + dx[i];
				to.ty = now.ty + dy[i];
				to.kx = now.kx - dx[i];
				to.ky = now.ky - dy[i];
			}
			
			if (d[to.tx][to.ty][to.kx][to.ky] == INF /* && d[now.tx][now.ty][now.kx][now.ky] < 100 */){
				que.push(to);
				d[to.tx][to.ty][to.kx][to.ky] = d[now.tx][now.ty][now.kx][now.ky] + 1;
			}
		}
	}
	
	return (-1);
}

int main()
{
	while (scanf("%d %d", &X, &Y), X + Y){
		scanf("%d %d", &f.tx, &f.ty);
		scanf("%d %d", &f.kx, &f.ky);
		
		for (int i = 0; i < 52; i++){
			for (int j = 0; j < 52; j++){
				maze[i][j] = true;
			}
		}
		
		for (int i = 1; i <= Y; i++){
			for (int j = 1; j <= X; j++){
				scanf("%d", &maze[j][i]);
			}
		}
		
		int r = search();
		if (r != -1 || r <= 100) printf("%d\n", r);
		else puts("NA");
	}
	
	return 0;
}

C++: #include<cstdio>
#include<iostream>
#include<algorithm>
#include<queue>
#include<cstring>
#include<cstdlib>
using namespace std;
struct Data{
	int x1,y1,x2,y2,cnt;
	Data(){}
	Data(int x1,int y1,int x2,int y2,int cnt):
		x1(x1),y1(y1),x2(x2),y2(y2),cnt(cnt){}
};
bool memo[50][50][50][50];
int dx[] = {0,1,-1,0}, dy[] = {1,0,0,-1};
int main() {
	int x,y;
	while(scanf("%d%d",&x,&y),(x|y)) {
		int tx,ty;
		int kx,ky;
		scanf("%d%d",&tx,&ty);
		scanf("%d%d",&kx,&ky);
		tx--;ty--;kx--;ky--;
		int stage[51][51];
		for(int i = 0; i < y; i++) {
			for(int j = 0; j < x; j++) {
				scanf("%d",&stage[i][j]);
			}
		}
		memset(memo,0,sizeof(memo));
		queue<Data> Q;
		Q.push(Data(tx,ty,kx,ky,0));
		int ans = -1;
		while(!Q.empty()) {
			Data d = Q.front();Q.pop();
			if(d.cnt >= 100) break;
			if(d.x1 == d.x2 && d.y1 == d.y2) {
				ans = d.cnt;
				break;
			}
			if(memo[d.x1][d.y1][d.x2][d.y2]) continue;
			memo[d.x1][d.y1][d.x2][d.y2] = true;
			for(int i = 0; i < 4; i++) {
				bool flg1 = false,flg2 = false;
				int nx1 = dx[i] + d.x1, ny1 = dy[i] + d.y1;
				int nx2 = dx[3-i] + d.x2, ny2 = dy[3-i] + d.y2;
				if(nx1 < 0 || nx1 >= x || ny1 < 0 || ny1 >= y || stage[ny1][nx1] == 1) flg1 = true;
				if(nx2 < 0 || nx2 >= x || ny2 < 0 || ny2 >= y || stage[ny2][nx2] == 1) flg2 = true;
				if(!(flg1 | flg2)) {
					Q.push(Data(nx1,ny1,nx2,ny2,d.cnt + 1));
				}
				if(!flg1 && flg2) {
					Q.push(Data(nx1,ny1,d.x2,d.y2,d.cnt+1));
				}
				if(flg1 && !flg2) {
					Q.push(Data(d.x1,d.y1,nx2,ny2,d.cnt+1));
				}
			}
		}
		if(ans == -1) puts("NA");
		else printf("%d\n",ans);
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

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

using pi = pair<int, int>;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int w, h;
  while(cin >> w >> h, h != 0) {
    int tx, ty, kx, ky;
    cin >> tx >> ty >> kx >> ky;
    vector<vector<int>> d(h + 2, vector<int>(w + 2, 1));
    for(int i = 1; i <= h; ++i) {
      for(int j = 1; j <= w; ++j) {
        cin >> d[i][j];
      }
    }

    map<pair<pi, pi>, int> mp;
    queue<pair<pi, pi>> que;
    pair<pi, pi> now({{tx, ty}, {kx, ky}}), nxt;
    que.push(now);
    mp[now] = 0;

    int ans = 1e9;
    while(!que.empty()) {
      now = que.front();
      que.pop();

      if(mp[now] >= 100) break;
      if(now.first.first == now.second.first && now.first.second == now.second.second) {
        ans = mp[now];
        break;
      }

      for(int i = 0; i < 4; ++i) {
        int ntx = now.first.first + dx[i];
        int nty = now.first.second + dy[i];
        int nkx = now.second.first - dx[i];
        int nky = now.second.second - dy[i];
        if(d[nty][ntx] == 1) {
          ntx -= dx[i]; nty -= dy[i];
        }
        if(d[nky][nkx] == 1) {
          nkx += dx[i]; nky += dy[i];
        }

        nxt = {{ntx, nty}, {nkx, nky}};
        if(!mp.count(nxt)) {
          mp[nxt] = mp[now] + 1;
          que.push(nxt);
        }
      }
    }

    if(ans == 1e9) cout << "NA\n";
    else cout << ans << endl;
  }
}