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<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<time.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double EPS=1e-10;
const int inf=1e8;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
int sx,sy;
int gx,gy;
vvi tmp;
int dx[]={0,0,1,-1};
int dy[]={-1,1,0,0};
void solve(int x,int y){
	tmp[x][y]=-1;
	rep(i,4){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(tmp[nx][ny]==2)solve(nx,ny);
	}
}
int main(){
	int n,m;
	while(cin>>n>>m,n+m){
		vvi in(n+2,vi(m+2));
		cin>>sx>>sy>>gx>>gy;
		cin>>n;
		while(n--){
			int a,b,c,d;
			cin>>a>>b>>c>>d;
			if(!b)rep(i,4)rep(j,2)in[c+i][d+j]=a;
			else rep(i,2)rep(j,4)in[c+i][d+j]=a;
		}
		tmp=in;
		if(in[sx][sy]==2)solve(sx,sy);
		//rep(i,in.size()){rep(j,in[0].size())cout<<in[i][j]<<" ";cout<<endl;}
		//cout<<endl;
		//rep(i,tmp.size()){rep(j,tmp[0].size())cout<<tmp[i][j]<<" ";cout<<endl;}
		cout<<((in[sx][sy]==2&&in[gx][gy]==2&&tmp[gx][gy]==-1)?"OK":"NG")<<endl;
		//rep(i,22){rep(j,22)cout<<tmp[i][j]<<" ";cout<<endl;}
	}
}

C++: #include<iostream>
using namespace std;
#define MAX 100

int map[MAX][MAX];
int xs, ys, xg, yg;
int n;
int w, h;
int c, d, x, y;
int count = 0;
int color;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

void jadge(int x, int y){
	if(count == 0){
		if(0 <= x && x < w && 0 <= y && y < h && map[x][y] == color){
			map[x][y] = 9;
			if(x == xg && y == yg){
				count = 1;
				return;
			}
			for(int i=0; i < 4; i++){
				jadge(x+dx[i], y+dy[i]);
			}
		}
	}
}
int main(){
	while(1){
		count = 0;

		for(int i=0; i < MAX; i++){
			for(int j=0; j< MAX; j++){
				map[i][j] = 0;
			}
		}

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

		cin >> xs >> ys;
		cin >> xg >> yg;
		xs--; ys--; xg--; yg--;
		cin >> n;
		for(int i=0; i < n; i++){
			cin >> c >> d >> y >> x;

			for(int i=0;  i < 4; i++){
				for(int j=0; j < 2; j++){
					if(d == 1){
						map[x-1+i][y-1+j] = c;
					}
					else{
						map[x-1+j][y-1+i] = c;
					}
				}
			}
		}
		if(map[xs][ys] != map[xg][yg]){
			cout << "NG" << endl;
			continue;
		}
		else if(map[xs][ys] == 0 || map[xg][yg] == 0){
			cout << "NG" << endl;
			continue;
		}
		color = map[xs][ys];

		jadge(xs, ys);

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