Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

var (
	dx = []int{0, -1, 0, 1}
	dy = []int{1, 0, -1, 0}
)

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		w, _ := strconv.Atoi(buf[0])
		h, _ := strconv.Atoi(buf[1])
		if w == 0 && h == 0 {
			break
		}
		scanner.Scan()
		buf_ := strings.Split(scanner.Text(), " ")
		xs, _ := strconv.Atoi(buf_[0])
		ys, _ := strconv.Atoi(buf_[1])
		scanner.Scan()
		buf__ := strings.Split(scanner.Text(), " ")
		xg, _ := strconv.Atoi(buf__[0])
		yg, _ := strconv.Atoi(buf__[1])
		xs--
		ys--
		xg--
		yg--
		scanner.Scan()
		n, _ := strconv.Atoi(scanner.Text())
		field := make([][]int, 100)
		for i := range  field {
			field[i] = make([]int, 100)
		}
		visited := make([][]bool, 100)
		for i := range visited {
			visited[i] = make([]bool, 100)
		}
		for i := 0; i < n; i++ {
			scanner.Scan()
			buf___ := strings.Split(scanner.Text(), " ")
			c, _ := strconv.Atoi(buf___[0])
			d, _ := strconv.Atoi(buf___[1])
			x, _ := strconv.Atoi(buf___[2])
			y, _ := strconv.Atoi(buf___[3])
			x--
			y--
			switch d {
			case 0:
				for j := 0; j < 4; j++ {
					for k := 0; k < 2; k++ {
						field[x+j][y+k] = c
					}
				}
			case 1:
				for j := 0; j < 2; j++ {
					for k := 0; k < 4; k++ {
						field[x+j][y+k] = c
					}
				}
			}
		}
		if field[xs][ys] != field[xg][yg] || // スタートとゴールの色が等しくないと"NG"
			field[xs][ys] == 0 { // スタートの色が無職
			fmt.Println("NG")
			continue
		}
		Q := make([]Entry, 0)
		visited[xs][ys] = true
		Q = append(Q, Entry{xs, ys})
		for len(Q) > 0 {
			row := Q[0].x
			col := Q[0].y
			Q = Q[1:]
			for i := 0; i < 4; i++ {
				if 0 <= row+dx[i] && row+dx[i] < w &&
					0 <= col+dy[i] && col+dy[i] < h && // 移動可能な範囲内かどうか
					!visited[row + dx[i]][col + dy[i]] && // 訪問済みか
					field[row+dx[i]][col+dy[i]]==field[row][col] { // 色が同じかどうか
						visited[row+dx[i]][col+dy[i]] = true
						Q = append(Q, Entry{row+dx[i],col+dy[i]})
				}
			}
		}
		if visited[xg][yg] {
			fmt.Println("OK")
		} else {
			fmt.Println("NG")
		}
	}
}

type Entry struct {
	x, y int
}

C++: #define _USE_MATH_DEFINES
#include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<climits>
#include<map>
#include<string>
using namespace std;

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

struct Data{
	int y, x;
	Data(){}
	Data(int _y, int _x){
		y = _y; x = _x;
	}
};

int fld[100][100];

void PaintFld(int c, int x, int y, int w, int h){
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			fld[y + i][x + j] = c;
		}
	}
}

int main(){
	int W, H;
	while(cin >> W >> H, W || H){
		fill_n( (int*)fld, 100*100, 0 );
		int Xs, Ys, Xg, Yg, N, C, D, X, Y;
		cin >> Xs >> Ys >> Xg >> Yg >> N;
		Xs--; Ys--; Xg--; Yg--;
		for(int i = 0; i < N; i++){
			cin >> C >> D >> X >> Y;
			X--; Y--;
			if(D == 0) PaintFld(C, X, Y, 4, 2);
			else PaintFld(C, X, Y, 2, 4);
		}

		queue<Data> q;
		Data q_front;
		bool memo[100][100] = {}, ans = false;
		q.push( Data(Xs, Ys) );
		while( !q.empty() ){
			q_front = q.front(); q.pop();

			if(fld[q_front.y][q_front.x] == 0 ||
			   fld[q_front.y][q_front.x] != fld[Ys][Xs])
				continue;

			if(q_front.y == Yg && q_front.x == Xg){
				ans = true; break;
			}

			if(memo[q_front.y][q_front.x]) continue;
			memo[q_front.y][q_front.x] = true;

			for(int i = 0; i < 4; i++){
				int ny = q_front.y + dy[i];
				int nx = q_front.x + dx[i];

				if(ny < 0 || H <= ny || nx < 0 || W <= nx)
					continue;
				q.push( Data(ny, nx) );
			}
		}

		if(ans) puts("OK");
		else puts("NG");
	}
	return 0;
}

C++: #include<iostream>
#include<cstring>
#include<queue>
#include<map>
using namespace std;
int C,goal,n,x,y,xs,ys,xg,yg,mas[110][110]={{0}};
int dx[4]={0,0,1,1};
int dy[4]={0,1,0,1};
int d[110][110];
typedef pair<int,int>P;

int bfs();
int main(){

  while(1){
    goal=0;
    memset(mas,0,sizeof(mas));
    cin >> x >> y;//ボードの大きさ。 ※：x=横。y=縦。
    if(x==0 && y==0){
      break;
    }
    cin >> xs >> ys;//スタート地点。
    cin >> xg >> yg;//ゴール地点。
    cin >> n;//ブロックの数。
    
    //色染め。
    int color,dire,xx,yy;
    for(int t=0;t<n;t++){
      cin >> color >> dire >> xx >> yy;

      //横長。
      if(dire==0){
	for(int i=0;i<2;i++){
	  for(int j=0;j<4;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
      //縦長。
      else{
	for(int i=0;i<4;i++){
	  for(int j=0;j<2;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
    }
    
    //通る色　摘出。
    C=mas[ys][xs];
    //cout << "color:" << C << endl;
    
    if(color!=0){
      bfs();

    
      if(goal==1){
	cout << "OK" << endl;
      }
      else{
	cout << "NG" << endl;
      }
    }
    else{
      cout << "NG" << endl;
    }
  }
}

int bfs(){
  queue<P>que;
  memset(d,-1,sizeof(d));
  que.push(P(ys,xs));
  d[ys][xs]=0;
  while(!que.empty()){
    P p=que.front();
    que.pop();
    if(p.first==yg && p.second==xg){
      goal=1;
      break;
    }
    for(int i=0;i<4;i++){
      int ny=p.first+dy[i];
      int nx=p.second+dx[i];
      if(mas[ny][nx]==C && ny>=1 && ny<=y && nx>=1 && nx<=x && d[ny][nx]==-1){
	que.push(P(ny,nx));
	d[ny][nx]=0;
      }
    }
  }
  return (0);
}

C++: #include<iostream>
#include<stack>
#include<cstdio>
using namespace std;

#define X_MAX 100+10
#define Y_MAX 100+10

#define Vertical 1
#define Horizontal 0

int my[4] = { 1,-1,0,0 };
int mx[4] = { 0,0,1,-1 };

struct ST
{
	int came[Y_MAX][X_MAX];
	int now_y;
	int now_x;
};


void paint_V(int*map , int col)
{
	int i;
	for (i = 0; i < 2; i++)
	{
		*(map + i) = col;
	}
}

void paint_H(int*map, int col)
{
	int i;
	for (i = 0; i < 4; i++)
	{
		*(map + i) = col;
	}
}


void chek(int map[Y_MAX][X_MAX],int lx,int ly)
{
	int i, j;
	for (i = 0; i <= ly+1;i++)
	{
		for (j = 0; j <= lx+1; j++)
		{
			cout << map[i][j];
		}
		cout << endl;
	}
}


int main(void)
{
	ST an = {0}, tmp;
	stack<ST> ma;

	int lx, ly, n;
	int sx, sy, gx, gy;
	int col, VorH,set_x,set_y;
	int i, j;

	while ((cin >> lx >> ly), lx!=0&&ly!=0)
	{
		int goal = 0;
		int map[Y_MAX][X_MAX] = { 0 };
		cin >> sx >> sy >> gx >> gy >> n;

		for (i = 0; i < n; i++)
		{
			cin >> col >> VorH >> set_x >> set_y;
			if (VorH == Vertical)
			{
				for (j = 0; j < 4; j++)
				{
					paint_V(map[set_y + j] + set_x, col);
				}
			}
			else
			{
				for (j = 0; j < 2; j++)
				{
					paint_H(map[set_y + j] + set_x, col);
				}
			}
		}
		
		int s_col = map[sy][sx];
		if (s_col == 0)
		{
			cout << "NG\n";
			continue;
		}

		an.now_y = sy;
		an.now_x = sx;
		ma.push(an);

		//chek(map, lx, ly);

		while (!ma.empty())
		{
			an = ma.top();
			ma.pop();
			an.came[an.now_y][an.now_x] = 1;

			//printf("y=%d,x=%d\n", an.now_y, an.now_x);
			//chek(an.came, lx, ly);

			if (an.now_y == gy && an.now_x == gx)
			{
				goal = 1;
				break;
			}

			tmp = an;

			for (i = 0; i < 4; i++)
			{
				if (map[an.now_y + my[i]][an.now_x + mx[i]] == s_col && an.came[an.now_y + my[i]][an.now_x + mx[i]] == 0)
				{
					tmp.now_y = an.now_y + my[i];
					tmp.now_x = an.now_x + mx[i];
					ma.push(tmp);
				}
			}

		}
		if (goal == 1)
		{
			while (!ma.empty())
			{
				ma.pop();
			}
			cout << "OK\n";
		}
		else
		{
			cout << "NG\n";
		}


	}
	return 0;
}