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>
using namespace std;

int block[100][100];
int xs, ys, xg, yg, n, w, h;

bool dfs(int x, int y, int c)
{
  if(block[x][y] != c || block[x][y] == 0)
    return false;
  if(x == xg && y == yg)
    return true;
  bool b = false;
  block[x][y] = 0;
  if(x < w - 1)
    b |= dfs(x + 1, y, c);
  if(x > 0 && !b)
    b |= dfs(x - 1, y, c);
  if(y < h - 1 && !b)
    b |= dfs(x, y + 1, c);
  if(y > 0 && !b)
    b |= dfs(x, y - 1, c);
  return b;
}

int main()
{
  while(true)
  {
    cin >> w >> h;
    if(!w && !h)
      break;
    cin >> xs >> ys
      >> xg >> yg >> n;
    xs--; ys--;
    xg--; yg--;
    
    for(int i = 0; i < n; i++)
    {
      int c, d, x, y;
      cin >> c >> d >> x >> y;
      x--; y--;
      block[x][y] = c;
      block[x + 1][y] = c;
      block[x][y + 1] = c;
      block[x + 1][y + 1] = c;
      if(d == 0)
        x += 2;
      else
        y += 2;
      block[x][y] = c;
      block[x + 1][y] = c;
      block[x][y + 1] = c;
      block[x + 1][y + 1] = c;
    }
    if(dfs(xs, ys, block[xs][ys]))
      cout << "OK\n";
    else
      cout << "NG\n";
  }
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define FFOR(i,a,b) for(int i=(a);i<=(b);i++)
#define REP(i,b) FOR(i,0,b)
#define RREP(i,b) FFOR(i,1,b)
#define PB push_back
#define F first
#define S second
#define BE(c) c.begin(),c.end()
using namespace std;
typedef long long LL;
typedef LL ut;
typedef long double ld;
typedef pair<ut,ut> pr;
typedef vector<pr> Vpr;
typedef vector<ut> VI;
typedef pair<ut,pr> ppr;
typedef priority_queue<pr,Vpr, greater<pr> > PQ;
const int SIZE=5+3*1e+4;
const ut INF=1<<30;
const ld eps=1e-6;
const LL p=7+1e+9;

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

int W, H;
int xs, ys, xg, yg;
int N, C;
int maze[128][128];
bool check[128][128];

int dfs(int x, int y){
	if(x == xg && y == yg)
		return 1;
	
	int res = 0;
	REP(i,4){
		int nx = x + dx[i];
		int ny = y + dy[i];
		if(nx > 0 && nx <= W && ny > 0 && ny <= H && !check[ny][nx] && maze[ny][nx] == C){
			check[ny][nx] = true;
			res |= dfs(nx, ny);
		}
	}
	return res;
}

int main(){
	while(cin >> W >> H && (W || H)){
		memset(maze, 0, sizeof(maze));
		memset(check, 0, sizeof(check));
		cin >> xs >> ys >> xg >> yg >> N;
		int c, d, x, y;
		REP(i,N){
			cin >> c >> d >> x >> y;
			if(d == 0){
				REP(j,2)
					REP(k,4)
						maze[y + j][x + k] = c;
			}
			else{
				REP(j,4)
					REP(k,2)
						maze[y + j][x + k] = c;
			}
		}
		C = maze[yg][xg];
		check[ys][xs] = true;
		int ans = dfs(xs, ys);
		if(ans){
			cout << "OK" << endl;
		}
		else{
			cout << "NG" << endl;
		}
	}
}

C++: #include<cstdio>
#include<iostream>
#include<string>
#include<string.h>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<stdlib.h>
#include<queue>
#include<map>
#include<vector>
#include<list>
#include<stack>
#include<functional>
 
using namespace std;
 
#define all(c) (c).begin(), (c).end()
#define rep(i,n) for(int i=0;i<n;i++)

 
const int INF=100000000;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
 
typedef pair<int ,int > P;
 
char maze[105][105];
 
int sx,sy;
int gx,gy;
int w,h;
 
char sc;        //スタート地点のカラー
 
//stdin
//stdout
 
void dfs(int x,int y)
{
    maze[y][x]='9';
 
    rep(i,4)
    {
/*        for(int j=-1;j<=1;j++)
        {*/
            int nx=x+dx[i];
            int ny=y+dy[i];
 
            if(0<=nx && nx<=w && 0<=ny && ny<=h &&maze[ny][nx]==sc)
            {
                dfs(nx,ny);
            }
 
/*        }*/
    }
    return ;
}
 
void solve()
{
 
    rep(i,101)
        rep(j,101)
        maze[i][j]='0';
 
    int n;
    char c;
    int d;
    int x,y;
 
    cin>>sx>>sy;
    cin>>gx>>gy;
 
    cin>>n;
 
    rep(i,n)
    {
        cin>>c>>d>>x>>y;
 
        if(d==1)
        {
            rep(j,2)
            {
                rep(k,4)
                {
                    maze[y+k][x+j]=c;
 
                }
            }
        }
        else if (d==0)
        {
            rep(j,4)
            {
                rep(k,2)
                {
                    maze[y+k][x+j]=c;
 
                }
            }
        }
 
    }
//6 6
//1 1
//3 6
//2
//1 0 1 1
//1 1 3 3
//  rep(i,w+1)
//  {
//      rep(j,h+1)
//      {
//          cout<<maze[i][j];
//
//      }
//      cout<<endl;
//  }
//
//  cout<<maze[gx][gy]<<endl;
 
    if(maze[sy][sx]=='0')
    {
        cout<<"NG"<<endl;
        return;
    }
    else
    {
        sc=maze[sy][sx];
        dfs(sx,sy);
    }
     
    //rep(i,w+1)
    //{
    //  rep(j,h+1)
    //  {
    //      cout<<maze[i][j];
 
    //  }
    //  cout<<endl;
    //}
 
    if(maze[gy][gx]=='9')
    {
        cout<<"OK"<<endl;
        return;
    }
    else
    {
        cout<<"NG"<<endl;
        return;
    }
 
 
 
}
 
int main()
{
 
    while(cin>>w>>h)
    {
        if(w==0 && h==0)
        {
            return 0;
        }
        else
        {
            solve();
        }
    }
 
 
    return 0;
}