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)
	pq = append(pq, 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)
		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 += 1
			if next.Turn <= 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				pq = append(pq, 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 <iostream>
#include <algorithm>
#include <queue>
#include <utility>
#include <map>
using namespace std;

const int Y = 50, X = 50, guard = -1;
typedef pair<int, int> P;


int bfs(const int (*board)[Y + 2], P t, P k){
	int dx[] = {0, -1, 1, 0}, dy[] = {-1, 0, 0, 1};
	// pair<P, P> -> first = t, second = k
	queue<pair<P, P> > q;
	map<pair<P, P>, int> visited;
	q.push(make_pair(t, k));
	visited[make_pair(t, k)] = 0;
	while(!q.empty()){
		pair<P, P> picked = q.front();
		q.pop();
		if(visited[picked] >= 100) break;
		P ct = picked.first, ck = picked.second;
		if(ct == ck) return visited[picked];
		for(int i = 0;i < 4;++i){
			pair<P, P> nextp;
			P nextt, nextk;
			int tdx, tdy, kdx, kdy;
			tdx = dx[i]; tdy = dy[i];
			kdx = -tdx; kdy = -tdy;
			nextt = board[ct.first + tdx][ct.second + tdy] != guard ? P(ct.first + tdx, ct.second + tdy) : ct;
			nextk = board[ck.first + kdx][ck.second + kdy] != guard ? P(ck.first + kdx, ck.second + kdy) : ck;
			nextp = make_pair(nextt, nextk);
			if(visited[nextp] == 0){
				q.push(nextp);
				visited[nextp] = visited[picked] + 1;
			}
		}
	}
	return -1;
}

int main(){
	int board[X + 2][Y + 2];
	int x, y, a, res;
	P t, k;
	while(cin >> x >> y, x && y){
		for(int i = 0;i <= X + 1;++i){
			fill(board[i], board[i] + (Y + 2), -1);
		}
		cin >> t.first >> t.second;
		cin >> k.first >> k.second;
		for(int i = 1;i <= y;++i){
			for(int j = 1;j <= x;++j){
				cin >> a;
				board[i][j] = -a;
			}
		}
		res = bfs(board, t, k);
		if(res != guard) cout << res << endl;
		else cout << "NA" << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<queue>
using namespace std;

bool d[50][50][50][50];
int X, Y, tx, ty, kx, ky;
int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0}, mem[50][50];
int main()
{
loop:
  cin >> X >> Y;
  if(!X)
    return 0;
  cin >> tx >> ty >> kx >> ky;
  tx--; ty--; kx--; ky--;
  for(int y = 0; y < Y; y++)
  {
    for(int x = 0; x < X; x++)
    {
      int a;
      cin >> a;
      mem[y][x] = a;
    }
  }

  fill_n((bool*)d, 50 * 50 * 50 * 50, false);
  
  queue<int> q;
  q.push(tx);
  q.push(ty);
  q.push(kx);
  q.push(ky);
  q.push(0);
  while(!q.empty())
  {
    int x1 = q.front(); q.pop();
    int y1 = q.front(); q.pop();
    int x2 = q.front(); q.pop();
    int y2 = q.front(); q.pop();
    int n = q.front(); q.pop();
    
    if(n == 100)
    {
      cout << "NA" << endl;
      break;
    }
    
    if(y1 == y2 && x1 == x2)
    {
      cout << n << endl;
      goto loop;
    }

    for(int i = 0; i < 4; i++)
    {
      int tx1 = x1 + dx[i];
      int ty1 = y1 + dy[i];
      int tx2 = x2 - dx[i];
      int ty2 = y2 - dy[i];

      bool b1 = ty1 < 0 || ty1 >= Y || tx1 < 0 || tx1 >= X || mem[ty1][tx1] == 1;
      bool b2 = ty2 < 0 || ty2 >= Y || tx2 < 0 || tx2 >= X || mem[ty2][tx2] == 1;

      if(b1)
      {
        tx1 = x1;
        ty1 = y1;
      }
      if(b2)
      {
        tx2 = x2;
        ty2 = y2;
      }
      if(d[tx1][ty1][tx2][ty2])
        continue; 

      d[tx1][ty1][tx2][ty2] = true;
      q.push(tx1);
      q.push(ty1);
      q.push(tx2);
      q.push(ty2);
      q.push(n + 1);
    }
  }
  cout << "NA" << endl;
  goto loop;
}

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[i][j]);
		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) {
				rep(j, 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:;
	}
}