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 <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <math.h>
#include <assert.h>
#include <vector>
#include <queue>

using namespace std;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
static const double EPS = 1e-9;
static const double PI = acos(-1.0);

#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define FOR(i, s, n) for (int i = (s); i < (int)(n); i++)
#define FOREQ(i, s, n) for (int i = (s); i <= (int)(n); i++)
#define FORIT(it, c) for (__typeof((c).begin())it = (c).begin(); it != (c).end(); it++)
#define MEMSET(v, h) memset((v), h, sizeof(v))

int w, h;
int sx, sy;
int gx, gy;
int n;
int field[120][120];

int main() {
  while (scanf("%d %d", &w, &h), w|h) {
    MEMSET(field, 0);
    scanf("%d %d", &sx, &sy);
    scanf("%d %d", &gx, &gy);
    scanf("%d", &n);
    REP(i, n) {
      int c, d, sx, sy;
      scanf("%d %d %d %d", &c, &d, &sx, &sy);
      int ex = sx + 2;
      int ey = sy + 2;
      if (d == 0) { ex += 2; }
      if (d == 1) { ey += 2; }
      FOR(y, sy, ey) {
        FOR(x, sx, ex) {
          field[y][x] = c;
        }
      }
    }
    int sc = field[sy][sx];
    queue<int> que;
    que.push(sy * w + sx);
    while (!que.empty()) {
      if (sc == 0) { break; }
      int x = que.front() % w;
      int y = que.front() / w;
      que.pop();
      if (x == gx && y == gy) {
        puts("OK");
        goto next;
      }
      REP(dir, 4) {
        const int dx[4] = { 1, 0, -1, 0 };
        const int dy[4] = { 0, 1, 0, -1 };
        int nx = x + dx[dir];
        int ny = y + dy[dir];
        if (field[ny][nx] != sc) { continue; }
        field[ny][nx] = 9;
        que.push(ny * w + nx);
      }
    }
    puts("NG");
next:;
  }
}

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

int F[102][102];

bool DFS(int X, int Y, int Xg, int Yg, int c){
	if(F[Y][X] != c){
		return false;
	}else if(F[Y][X] == c && X == Xg && Y == Yg){
		return true;
	}
	F[Y][X] = -1;
	if(DFS(X, Y - 1, Xg, Yg, c)){
		return true;
	}else if(DFS(X + 1, Y, Xg, Yg, c)){
		return true;
	}else if(DFS(X, Y + 1, Xg, Yg, c)){
		return true;
	}else if(DFS(X - 1, Y, Xg, Yg, c)){
		return true;
	}
	
	return false;
}

int main(){
bool isfirst = true;
while(true){
	if(isfirst){
		isfirst = false;
	}else{
		cout << endl;
	}
	int w, h;
	cin >> w >> h;
	if(w == 0 && h == 0){
		break;
	}
	int xs, ys, xg, yg;
	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;
		if(d == 0){
			for(int X = x; X < x + 4; X++){
				for(int Y = y; Y < y + 2; Y++){
					F[Y][X] = c;
				}
			}
		}else if(d == 1){
			for(int X = x; X < x + 2; X++){
				for(int Y = y; Y < y + 4; Y++){
					F[Y][X] = c;
				}
			}
		}
	}
	if(DFS(xs, ys, xg, yg, F[xg][yg])){
		cout << "OK";
	}else{
		cout << "NG";
	}
}
	return 0;
}

C++: #include <vector>
#include <iostream>
#include <cassert>

enum class Color {
	goal, white, yellow, green, blue, red, null
};
void recursive(std::vector<std::vector<Color>> &vector, const int &x, const int &y, const Color c) {
	if (0 <= x && x < vector.at(0).size() && 0 <= y && y < vector.size() && vector.at(y).at(x) == c) {
		vector.at(y).at(x) = Color::goal;
		recursive(vector, x, y - 1, c); recursive(vector, x + 1, y, c); recursive(vector, x, y + 1, c); recursive(vector, x - 1, y, c);
	}
}
void fill(std::vector<std::vector<Color>> &vector, const int &x, const int &y, const Color &c) {
	assert(0 <= x && 0 <= y && x < vector.at(0).size() && y < vector.size());
	for (auto i = 0; i < 2; ++i) {
		for (auto j = 0; j < 2; ++j) {
			vector.at(y + i).at(x + j) = c;
		}
	}
}
int main() {
	int w, h;
	std::cin >> w >> h;
	while (w != 0) {
		std::vector<std::vector<Color>> vector(h, std::vector<Color>(w, Color::null));
		int start_x, start_y;
		std::cin >> start_x >> start_y;
		int goal_x, goal_y;
		std::cin >> goal_x >> goal_y;
		int n;
		std::cin >> n;
		assert(start_x <= w && start_y <= h && goal_x <= w && goal_y <= h);
		for (auto i = 0; i < n; ++i) {
			int c, d, x, y;
			std::cin >> c >> d >> x >> y;
			fill(vector, x - 1, y - 1, Color(c));
			fill(vector, x + 1 - 2 * d, y - 1 + 2 * d, Color(c));
		}
		recursive(vector, start_x - 1, start_y - 1, vector.at(start_y).at(start_x));
		if (vector.at(goal_y - 1).at(goal_x - 1) == Color::goal) {
			std::cout << "OK\n";
		}
		else {
			std::cout << "NG\n";
		}
		std::cin >> w >> h;
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
  
int F[105][105];
int xg,yg;
  
  
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
  
  F[Y][X] = -2000;
  DFS(Y-1,X  ,c);
  DFS(Y  ,X+1,c);
  DFS(Y+1,X  ,c);
  DFS(Y  ,X-1,c);
}
  
  
int main(){
  int w,h,xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;

      
    cin >> xs >> ys >> xg >> yg >> n;
    int c[n],d[n],x[n],y[n],ca;
    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];
    }
    for(int i=0;i<n;i++){
      if(c[i] == 0)
        ca = 10;
      else if(i == n-1)
        ca = 0;
    }
    for(int i=0; i<102; i++){
          for(int j=0; j<102; j++){
            F[i][j]=10;
          }
    }
    for(int i=0;i<n;i++){
      if(d[i] == 0){
        for(int j=0;j<4;j++){
          F[x[i]+j][y[i]] = c[i];
          F[x[i]+j][y[i]+1] = c[i];
        }
      } else {
        for(int j=0;j<4;j++){
          F[x[i]][y[i]+j] = c[i];
          F[x[i]+1][y[i]+j] = c[i];
        }
      }
    }
 
  DFS(xs,ys,F[xs][ys]);
  
  if(F[xg][yg] == -2000){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}