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
		}
		if ans<=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 <bits/stdc++.h>
using namespace std;
typedef tuple<int, int, int, int, int> T;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int main() {
    while (true) {
        int W, H;
        cin >> W >> H;
        
        if (W==0 && H==0) {
            break;
        }
        
        int tx, ty;
        cin >> tx >> ty;
        tx -= 1;
        ty -= 1;
        
        int kx, ky;
        cin >> kx >> ky;
        kx -= 1;
        ky -= 1;
        
        int d[H][W];
        
        for (int i=0; i<H; i++) {
            for (int j=0; j<W; j++) {
                cin >> d[i][j];
            }
        }
        
        int visited[H][W][H][W];
        
        for (int i=0; i<H; i++) {
            for (int j=0; j<W; j++) {
                for (int k=0; k<H; k++) {
                    for (int l=0; l<W; l++) {
                        visited[i][j][k][l] = -1;
                    }
                }
            }
        }
        
        queue<T> q;
        q.push(make_tuple(ty, tx, ky, kx, 0));
        
        bool flag = false;
        
        while (q.size()) {
            T t = q.front(); q.pop();
            int i1 = get<0>(t);
            int j1 = get<1>(t);
            int i2 = get<2>(t);
            int j2 = get<3>(t);
            int cost = get<4>(t);
            
            if (cost==100) {
                continue;
            }
            
            if (i1==i2 && j1==j2) {
                cout << cost << endl;
                flag = true;
                break;
            }
            
            for (int i=0; i<4; i++) {
                int ni1 = i1+dx[i];
                int nj1 = j1+dy[i];
                int ni2 = i2-dx[i];
                int nj2 = j2-dy[i];
                
                if (!(0<=ni1 && ni1<H && 0<=nj1 && nj1<W)) {
                    ni1 = i1;
                    nj1 = j1;
                }
                else if (d[ni1][nj1]==1) {
                    ni1 = i1;
                    nj1 = j1;
                }
                
                if (!(0<=ni2 && ni2<H && 0<=nj2 && nj2<W)) {
                    ni2 = i2;
                    nj2 = j2;
                }
                else if (d[ni2][nj2]==1) {
                    ni2 = i2;
                    nj2 = j2;
                }
                
                if (visited[ni1][nj1][ni2][nj2]==-1) {
                    visited[ni1][nj1][ni2][nj2] = 1;
                    q.push(make_tuple(ni1, nj1, ni2, nj2, cost+1));
                }
            }
        }
        
        if (flag) {
            continue;
        }
        
        cout << "NA" << endl;
    }
}