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 <bits/stdc++.h>

using namespace std;

int w, h;
int gx, gy;
int vx[] = {0, 1, 0, -1};
int vy[] = {1, 0, -1, 0};
int block[100][100];
bool check[100][100];
bool flag;

void dfs(int y, int x) {

  /*
  for(int i = 0; i < h; ++i) {
    for(int j = 0; j < w; ++j) {
      if(i == y && j == x) cout << 'P';
      else if(i == gy && j == gx) cout << 'G';
      else cout << block[i][j];
    }
    cout << endl;
  }
  cout << endl;
  */

  if(y == gy && x == gx) {
    
    flag = true;
    return;

  } else {
    
    for(int i = 0; i < 4; ++i) {
      
      int ny = y + vy[i];
      int nx = x + vx[i];
      
      if(ny >= 0 && ny < h && nx >= 0 && nx < w && !check[ny][nx] && block[ny][nx] && block[ny][nx] == block[y][x]) {
	
	check[ny][nx] = true;
	dfs(ny, nx);
	check[ny][nx] = false;

      }

    }

  }

}

int main() {

  int sx, sy;
  int n;
  int c, d, x, y;

  while(cin >> w >> h) {

    if(w == 0 && h == 0) break;

    cin >> sx >> sy;
    cin >> gx >> gy;
    cin >> n;

    --sx;
    --sy;
    --gx;
    --gy;

    for(int i = 0; i < h; ++i) {
      for(int j = 0; j < w; ++j) {
	block[i][j] = 0;
	check[i][j] = false;
      }
    }

    for(int i = 0; i < n; ++i) {
	
	cin >> c >> d >> x >> y;

	--x;
	--y;
	
	int bw, bh;

	if(d) {
	  bw = 2;
	  bh = 4;
	} else {
	  bw = 4;
	  bh = 2;
	}

	for(int j = 0; j < bh; ++j) {
	  for(int k = 0; k < bw; ++k) {
	    block[y + j][x + k] = c;
	  }
	}

    }

    flag = false;
    check[sy][sx] = true;
    dfs(sy, sx);

    cout << (flag ? "OK" : "NG") << endl;

  }

}

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

void putblock(int x,int y,int c,int d);
bool bfs(std::pair<int,int> start,std::pair<int,int> goal);

std::queue< std::pair<int,int> > que;
int board[102][102];
bool visited[102][102];

int main()
{
	int n,w,h,x,y,c,d,xs,ys,xg,yg;
	
	while(1)
	{
		while(!que.empty()){que.pop();}
		memset(board,0,sizeof(board));
		memset(visited,0,sizeof(visited));
		std::cin>>w>>h;
		if(w==0&&h==0)break;
		std::cin>>xs>>ys>>xg>>yg>>n;
		for(int i=0;i<n;i++)
		{
			std::cin>>c>>d>>x>>y;
			putblock(x,y,c,d);
		}
		if(bfs(std::pair<int,int>(xs,ys),std::pair<int,int>(xg,yg)))
		{
			std::cout<<"OK"<<std::endl;
		}
		else
		{
			std::cout<<"NG"<<std::endl;
		}
	}
	return 0;
}

void putblock(int x,int y,int c,int d)
{
	int h,w;
	if(d==0)
	{
		h=2;
		w=4;
	}
	else
	{
		h=4;
		w=2;
	}
	for(int i=y;i<y+h;i++)
	{
		for(int j=x;j<x+w;j++)
		{
			board[i][j]=c;
		}
	}
}

bool bfs(std::pair<int,int> start,std::pair<int,int> goal)
{
	int x,y;
	if(board[start.second][start.first]==0||board[goal.second][goal.first]==0)return false;
	que.push(start);
	while(!que.empty())
	{
		x=que.front().first;
		y=que.front().second;
		que.pop();

		if(!visited[y][x])
		{
			visited[y][x]=true;
			if(board[y-1][x]==board[y][x])que.push(std::pair<int,int>(x-1,y));
			if(board[y+1][x]==board[y][x])que.push(std::pair<int,int>(x+1,y));
			if(board[y][x-1]==board[y][x])que.push(std::pair<int,int>(x,y-1));
			if(board[y][x+1]==board[y][x])que.push(std::pair<int,int>(x,y+1));

			if(x==goal.first&&y==goal.second)
			{
				return true;
			}
		}
	}
	return false;
}

C++: #include<iostream>
#define rep(i,n) for(int i=0;i<n;i++)
#define ck(a,b) 0<a&&a<=b
using namespace std;
int dy[]={-1,0,1,0},dx[]={0,-1,0,1};
int w,h,xs,ys,xg,yg,n,c,d,x,y,f[101][101];
bool dfs(int y,int x){
	f[y][x]=0;
	if(y==yg&&x==xg)return 1;
	bool r=0;
	rep(d,4){
		int ny=y+dy[d],nx=x+dx[d];
		if(ck(ny,h)&&ck(nx,w)&&f[ny][nx]==c)r=r||dfs(ny,nx);
	}
	return r;
}
int main(){
	while(cin>>w>>h,w){
		rep(i,h)rep(j,w)f[i+1][j+1]=0;
		cin>>xs>>ys>>xg>>yg>>n;
		rep(i,n){
			cin>>c>>d>>x>>y;
			rep(j,(d?2:4))rep(k,(d?4:2))f[y+k][x+j]=c;
		}
		c=f[ys][xs];
		cout<<(c>0&&dfs(ys,xs)?"OK":"NG")<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<math.h>
#include<string>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
#include<utility>
#include<set>
#include<map>
#include<stdlib.h>
#include<iomanip>

using namespace std;

#define ll long long
#define ld long double
#define EPS 0.0000000001
#define INF 1e9
#define rep(i,n) for(i=0;i<n;i++)
#define loop(i,a,n) for(i=a;i<n;i++)
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)

typedef vector<int> vi;
typedef pair<int,int> pii;

int i,j;
int a[105][105];
int used[105][105];
int h,w;

void search(int y,int x,int c){
  if(x<0 || y<0 || y>=h || x>=w || a[y][x]!=c)return;
  if(used[y][x])return;
  used[y][x]++;
  int i;
  int dx[4]={-1,0,1,0};
  int dy[4]={0,-1,0,1};
  rep(i,4)
    search(y+dy[i],x+dx[i],c);
  return;
}
int main(void) {
  while(1){
    cin>>h>>w;
    if(h==0 && w==0)break;
    rep(i,h)rep(j,w)used[i][j]=0;
    int xs,ys,xg,yg,n;
    cin>>xs>>ys;
    xs--;ys--;
    cin>>xg>>yg;
    xg--;yg--;
    cin>>n;
    rep(i,n){
      int c,d,x,y;
      cin>>c>>d>>x>>y;
      x--;y--;
      int p[8]={0,0,0,0,1,1,1,1};
      int q[8]={0,1,2,3,0,1,2,3};
      if(d)
        rep(j,8)
          a[y+q[j]][x+p[j]]=c;
      else
        rep(j,8)
          a[y+p[j]][x+q[j]]=c;
    }
    if(a[ys][xs]==0){
      cout<<"NG"<<endl;
      continue;
    }
    search(ys,xs,a[ys][xs]);//dfs                         
    if(used[yg][xg])
      cout<<"OK"<<endl;
    else
      cout<<"NG"<<endl;
  }
  return 0;
}