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++: #include<iostream>
#include<cstring>

using namespace std;

int map[105][105];
int xg,yg;
int w,h;
int dx[]={0,0,-1,1};
int dy[]={-1,1,0,0};

bool check(int x,int y)
{
  if(x==xg && y==yg)
    return true;
  if(map[x][y]==-1)
    return false;
  if(x>h||y>w||x<=0||y<=0)
    return false;
  
  char buf=map[x][y];
  map[x][y]=-1;
  for(int i=0;i<4;i++)
    {
      if(x+dx[i]<=h && x+dx[i]>=0 &&
	 y+dy[i]<=w && y+dy[i]>=0 &&
	 map[x+dx[i]][y+dy[i]]==buf && 
	 check(x+dx[i],y+dy[i])
	 )
	return true;
    }
  return false;
}
int main()
{
  for(;cin>>w>>h,w;)
    {
      memset(map,-1,sizeof(map));
      int xs,ys;
      cin>>xs>>ys;
      cin>>xg>>yg;
      int n;
      cin>>n;
      for(int i=0;i<n;i++)
	{
	  int c,d,x,y;
	  cin>>c>>d>>y>>x;
	  if(d==0)
	    {
	      for(int xx=x;xx<x+2;xx++)
		for(int yy=y;yy<y+4;yy++)
		  map[xx][yy]=c;
	    }
	  else
	    {
	      for(int xx=x;xx<x+4;xx++)
		for(int yy=y;yy<y+2;yy++)
		  map[xx][yy]=c;
	    }
	}
      if(check(xs,ys))
	cout<<"OK"<<endl;
      else 
	cout<<"NG"<<endl;      
    }
}

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

char F[102][102];
bool MazeJudge;
int xg,yg;

char ItoC(int i){
	if(i==1){
		return '1';
	}else if(i==2){
		return '2';
	}else if(i==3){
		return '3';
	}else if(i==4){
		return '4';
	}else if(i==5){
		return '5';
	}
}

void DFS(int X,int Y,char C)
{
	if(F[X][Y]!=C)
		return;

	F[X][Y] = '.';

	if(X==xg&&Y==yg){
		MazeJudge = true;
		return;
	}
	
	DFS(X-1,Y  ,C);
	DFS(X  ,Y+1,C);
	DFS(X+1,Y  ,C);
	DFS(X  ,Y-1,C);
}
	

int main()
{
	while(true){

		//デバッグ用迷路表示
		/*for(int j=0;j<102;j++){
			for(int i=0;i<102;i++){
				F[i][j] = '0';
			}
		}*/

		MazeJudge = false;
		int w,h;
		cin >> w >> h;
		if(w==0&&h==0)
			break;

		int xs,ys;
		cin >> xs >> ys >> xg >> yg;

		int n;
		cin >> n;
		for(int i=0;i<n;i++){
			int c,d,x,y;
			cin >> c >> d >> x >> y;
    			char color = ItoC(c);
			if(d==0){
				F[x  ][y  ] = color;
				F[x+1][y  ] = color;
				F[x+2][y  ] = color;
				F[x+3][y  ] = color;
				F[x  ][y+1] = color;
				F[x+1][y+1] = color;
				F[x+2][y+1] = color;
				F[x+3][y+1] = color;
			}else if(d==1){
				F[x  ][y  ] = color;
				F[x+1][y  ] = color;
				F[x  ][y+1] = color;
				F[x+1][y+1] = color;
				F[x  ][y+2] = color;
				F[x+1][y+2] = color;
				F[x  ][y+3] = color;
				F[x+1][y+3] = color;		
			}
		}
		
		//デバッグ用迷路表示
		/*for(int j=0;j<102;j++){
			for(int i=0;i<102;i++){
				cout << F[i][j];
			}
			cout << endl;
		}*/

		char rc = F[xs][ys];
		DFS(xs,ys,rc);
		if(MazeJudge==true){
			cout << "OK" << endl;
		}else if(MazeJudge==false){
			cout << "NG" << endl;
		}
	}

	return 0;
}