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>>ys>>xs;
      cin>>yg>>xg;
      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>
#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));
    memset(d,0,sizeof(d));
    C = goal = n = x = y = xs = ys = xg = yg = 0;

    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(C!=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(xs,ys));
  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(ny>=1 && ny<=y && nx>=1 && nx<=x && mas[ny][nx]==C && d[ny][nx]==-1){
	d[ny][nx] = 1;
	que.push(P(ny,nx));
      }
    }
  }
  return (0);
}

C++: #include<bits/stdc++.h>
using namespace std;

int xx[4] = {0, 1, 0, -1};
int yy[4] = {1, 0, -1, 0};
int block[101][101];
int already[101][101];
int w, h;
int xs, ys;
int xg, yg;
int n;
int dfs(int nowx, int nowy);

int main(){
  while(1){
    memset(block, 0, sizeof(block));
    memset(already, 0, sizeof(already));
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    cin >> xs >> ys;
    cin >> xg >> yg;
    cin >> n;
    for(int i = 0; i < n; i++){
      int c, d, x, y;
      cin >> c >> d >> x >> y;
      int high, wide;
      if(d){
	high = 4; wide = 2;
      }
      else{
	high = 2; wide = 4;
      }
      for(int j = 0; j < high; j++){
	for(int k = 0; k < wide; k++){
	  block[y+j][x+k] = c;
	}
      }
    }
    int ans = dfs(xs, ys);
    if(ans) cout << "OK" << endl;
    else cout << "NG" << endl;
  }
}

int dfs(int nowx, int nowy){
  int a = 0;
  already[nowy][nowx] = 1;
  if(nowx == xg && nowy == yg) return 1;
  for(int i = 0; i < 4; i++){
    int nextx = nowx + xx[i];
    int nexty = nowy + yy[i];
    if(0 < nextx && 0 < nexty && nextx <= w && nexty <= h && already[nexty][nextx] != 1 && block[nexty][nextx] == block[ys][xs]) a += dfs(nextx, nexty);
  }
  return a;
}

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));
    memset(d,0,sizeof(d));
    C = goal = n = x = y = xs = ys = xg = yg = 0;

    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(C!=0 && mas[ys][xs]==mas[yg][xg]){

      bfs();

    
      if(goal==1){
	cout << "OK" << endl;
	goal=0;
      }
      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(ny>=1 && ny<=y && nx>=1 && nx<=x && mas[ny][nx]==C && d[ny][nx]==-1){
	d[ny][nx] = 1;
	que.push(P(nx,ny));
      }
    }
  }
  return (0);
}