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(102)
	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]
			}
			if now==next {
				continue
			}
			next.Turn += 1
			if next.Turn <= 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				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 <algorithm>
#include <queue>
using namespace std;

const int INF = 1 << 29;

struct state {
    int dist;
    int tx, ty, kx, ky;
    state() {}
    state(int a, int b, int c, int d, int e): dist(a), tx(b), ty(c), kx(d), ky(e) {}
};

const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

int W, H, tx, ty, kx, ky;
int wall[50][50];

int memo[50][50][50][50];
int& get_memo(state st) {
    return memo[st.tx][st.ty][st.kx][st.ky];
}

state next_state(state st, int d) {
    int ntx = st.tx+dx[d], nty = st.ty+dy[d];
    if (0 <= ntx && ntx < H && 0 <= nty && nty < W &&
            wall[ntx][nty] == 0) {
        st.tx = ntx; st.ty = nty;
    }
    int nkx = st.kx+dx[(d+2)%4], nky = st.ky+dy[(d+2)%4];
    if (0 <= nkx && nkx < H && 0 <= nky && nky < W &&
            wall[nkx][nky] == 0) {
        st.kx = nkx; st.ky = nky;
    }
    st.dist += 1;
    return st;
}


int main() {
    while (true) {
        cin >> W >> H;
        if (W == 0 && H == 0) break;
        cin >> ty >> tx >> ky >> kx;
        --tx; --ty; --kx; --ky;
        for (int j = 0; j < H; ++j) {
            for (int k = 0; k < W; ++k) {
                cin >> wall[j][k];
            }
        }

        queue<state> que;
        que.emplace(0, tx, ty, kx, ky);

        for (int j = 0; j < H; ++j) {
            for (int k = 0; k < W; ++k) {
                for (int l = 0; l < H; ++l) {
                    fill(memo[j][k][l], memo[j][k][l]+W, INF);
                }
            }
        }
        memo[tx][ty][kx][ky] = 0;

        int ans = 101;

        while (!que.empty()) {
            state st = que.front(); que.pop();

            if (st.dist > 100) {
                break;
            }

            if (st.tx == st.kx && st.ty == st.ky) {
                ans = st.dist;
                break;
            }

            for (int d = 0; d < 4; ++d) {
                state nst = next_state(st, d);

                if (nst.dist < get_memo(nst)) {
                    get_memo(nst) = nst.dist;
                    que.emplace(nst);
                }
            }
        }

        if (ans > 100) {
            cout << "NA" << endl;
        } else {
            cout << ans << endl;
        }
    }
    return 0;
}

C++: #include <iostream>
#include <memory>
#include <memory.h>
#include <cmath>
#include <numeric>
#include <vector>
#include <stack>
#include <string>
#include <queue>
#include <sstream>
#include <cstdlib>
#include <cstdio>
#include <map>
using namespace std;
typedef long long ll;

int x, y;
int tm[51][51][51][51];
char field[51][51];
int dx[] = {
	0, -1, 0, 1
};
int dy[] = {
	1, 0, -1, 0
};
struct twins{
	int x1;
	int y1;
	int x2; 
	int y2;
};

bool can_move(int x1, int y1){
	if(x1 > 0 && x1 <= x && y1 > 0 && y1 <= y){
		if(field[y1][x1] == '0') return true;
		else return false;
	}
	return false;
}

void get_time(int x1, int y1, int x2, int y2){
	twins t0;
	t0.x1 = x1, t0.x2 = x2, t0.y1 = y1, t0.y2 = y2;
	queue<twins> qt;
	qt.push(t0);
	while(!qt.empty()){
		twins t = qt.front(); qt.pop();
		for(int i = 0; i < 4; i++){
			int ay = t.y1 + dy[i];
			int ax = t.x1 + dx[i];
			int by = t.y2 - dy[i];
			int bx = t.x2 - dx[i];
			if(!can_move(ax, ay)){
				ay = t.y1;
				ax = t.x1;
			}
			if(!can_move(bx, by)){
				by = t.y2;
				bx = t.x2;
			}
			if(tm[ay][ax][by][bx] < 0){
				tm[ay][ax][by][bx] = tm[t.y1][t.x1][t.y2][t.x2] + 1;
				t0.x1 = ax, t0.x2 = bx, t0.y1 = ay, t0.y2 = by;
				qt.push(t0);
			}
		}
	}
}

int main(){
	int ax, ay, bx, by;
	while(cin >> x >> y && (x || y)){
		int count = 101;
		memset(tm, -1, sizeof(tm));
		cin >> ax >> ay >> bx >> by;
		for(int i = 1; i <= y; i++){
			for(int j = 1; j <= x; j++){
				cin >> field[i][j];
			}
		}
		tm[ay][ax][by][bx] = 0;
		get_time(ax, ay, bx, by);
		for(int i = 1; i <= y; i++){
			for(int j = 1; j <= x; j++){
				if(tm[i][j][i][j] >= 0) count = min(count, tm[i][j][i][j]);
			}
		}
		if(count == 101) cout << "NA" << endl;
		else cout << count << endl;
	}
	return 0;
}