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<queue>
#include<iostream>
#include<algorithm>
#include <conio.h>
using namespace std;
struct maigo{
	int x[2];
	int y[2];
	int count = 1;
};
int main(){
	queue<maigo> q;
	int tx, ty; int kx, ky;
	int **depart, X, Y;
	int flag = 0, a = 0;
	cin >> X >> Y;
	while (X != 0 && Y != 0){
		depart = new int*[Y + 2];
		for (int i = 0; i < Y + 2; i++){
			depart[i] = new int[X + 2];
		}
		for (int i = 0; i < Y + 2; i++){
			for (int l = 0; l < X + 2; l++){
				depart[i][l] = 3;
			}
		}
		cin >> tx >> ty;
		cin >> kx >> ky;
		for (int i = 1; i < Y + 1; i++){
			for (int l = 1; l < X + 1; l++){
				cin >> depart[i][l];
			}
		}
		maigo temp;
		temp.x[0] = tx; temp.y[0] = ty;
		temp.x[1] = kx; temp.y[1] = ky;
		q.push(temp);
		while (!q.empty() && flag == 0){
			maigo t = q.front();
			q.pop();
			int dx1[4] = { 1, 0, -1, 0 }; int dx2[4] = { 0, 1, 0, -1 };
			for (int i = 0; i < 4; i++){
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] == 0 &&
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0){
					depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] = -1;
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] = -1;
					if (t.x[0] + dx1[i] == t.x[1] + dx1[i] * (-1) &&
						t.y[0] + dx2[i] == t.y[1] + dx2[i] * (-1)){
						cout << t.count << endl;
						flag = 1;
					}
					maigo into;
					into.x[0] = t.x[0] + dx1[i], into.y[0] = t.y[0] + dx2[i];
					into.x[1] = t.x[1] + dx1[i] * (-1), into.y[1] = t.y[1] + dx2[i] * (-1);
					into.count = t.count + 1;
					if (into.count >= 100){
						flag = 1;
						a = 1;
					}
					q.push(into);
				}
			}
		}if (a == 1||flag == 0) {
			cout << "NA" << endl;
		}while (!q.empty()) q.pop();
		a = 0; flag = 0;
		cin >> X >> Y;
	}
	return 0;
}

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];
vector<PP>Now[101];
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;
					}
				}
			}
		}
		
		
		PP x;
		x.fi.sc=tx;x.fi.fi=ty;x.sc.sc=kx;x.sc.fi=ky;
		Now[0].pb(x);
		int ans=1001;
		bool F=true;
		for(int i=0;i<100;i++){
			for(int j=0;F&&(j<(int)Now[i].size());j++){
				PP p=Now[i][j];
				S[p.fi.fi][p.fi.sc][p.sc.fi][p.sc.sc]=i;
				if(p.fi.fi==p.sc.fi&&p.fi.sc==p.sc.sc){
					ans=i;
					F=false;
				}
				for(int k=0;k<4;k++){
					PP t;
					if(p.fi.fi+dy[k]<0||p.fi.fi+dy[k]>=Y||p.fi.sc+dx[k]<0||p.fi.sc+dx[k]>=X){
						t.fi.fi=p.fi.fi;t.fi.sc=p.fi.sc;
					}
					else if(grid[p.fi.fi+dy[k]][p.fi.sc+dx[k]]==1){
						t.fi.fi=p.fi.fi;t.fi.sc=p.fi.sc;
					}
					else{
						t.fi.fi=p.fi.fi+dy[k];
						t.fi.sc=p.fi.sc+dx[k];
					}
					if(p.sc.fi-dy[k]<0||p.sc.fi-dy[k]>=Y||p.sc.sc-dx[k]<0||p.sc.sc-dx[k]>=X){
						t.sc.fi=p.sc.fi;t.sc.sc=p.sc.sc;
					}
					else if(grid[p.sc.fi-dy[k]][p.sc.sc-dx[k]]==1){
						t.sc.fi=p.sc.fi;t.sc.sc=p.sc.sc;
					}
					else{
						t.sc.fi=p.sc.fi-dy[k];
						t.sc.sc=p.sc.sc-dx[k];
					}
					if(S[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]<=i)continue;
					//if(i==1)printf("%d %d %d %d\n",t.fi.fi,t.fi.sc,t.sc.fi,t.sc.sc);
					Now[i+1].pb(t);
				}
			}
			Now[i].clear();
		}
		int i=100;
		for(int j=0;j<(int)Now[i].size();j++){
			if(Now[i][j].fi.fi==Now[i][j].sc.fi&&Now[i][j].fi.sc==Now[i][j].sc.sc){
				ans=100;
			}
		}
		Now[101].clear();
		if(ans==1001)printf("NA\n");
		else printf("%d\n",ans);
		
	}
	return 0;
}