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----------------------------------------------------------------------------------------------------------------------
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<string>
#include<cctype>
#include<string>
#include<vector>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<bitset>
#include<map>
#include<algorithm>
#include<memory>


//using namespace--------------------------------------------------------------------------------------------------------------
using namespace std;

//define,const-----------------------------------------------------------------------------------------------------------------
#define rep(i, n) for(int i = 0; i < n; i++)
const int INF = 1 << 25;
#define MAX 1000

//global-----------------------------------------------------------------------------------------------------------------------
int board_range_w, board_range_h, start_x, start_y, goal_x, goal_y;
int color[MAX][MAX];
bool dp[MAX][MAX];

//function---------------------------------------------------------------------------------------------------------------------
bool solve(int x, int y, int before_x, int before_y){
	if ( x == goal_x && y == goal_y )
		return true;
	if ( !color[x][y] ){
		dp[x][y] = false;
		return false;
	}
	if ( color[x][y] == color[x + 1][y] && x + 1 != before_x && dp[x + 1][y] )
		if ( solve(x + 1, y, x, y) )
			return true;
	if ( color[x][y] == color[x][y + 1] && y + 1 != before_y && dp[x][y + 1] )
		if ( solve(x, y + 1, x, y) )
			return true;
	if ( color[x][y] == color[x][y - 1] && y - 1 != before_y && dp[x][y - 1] )
		if ( solve(x, y - 1, x, y) )
			return true;
	if ( color[x][y] == color[x - 1][y] && x - 1 != before_x && dp[x - 1][y] )
		if ( solve(x - 1, y, x, y) )
			return true;
	dp[x][y] = false;
	return false;
}

int n, c[30000], d[30000];


int main(){
	while ( scanf("%d %d", &board_range_w, &board_range_h) ) {
		if ( board_range_w == 0 && board_range_h == 0 )
			return 0;
		for ( int i = 0; i < 1000; i++ ){
			for ( int j = 0; j < 1000; j++ ){
				color[i][j] = 0;
				dp[i][j] = true;
			}
		}
		scanf("%d %d", &start_x, &start_y);
		scanf("%d %d", &goal_x, &goal_y);
		int block;
		scanf("%d", &block);
		for ( int i = 0; i < block; i++ ){
			//ブロック情報
			int block_color, block_quarter, block_start_x, block_start_y;
			scanf("%d %d %d %d", &block_color, &block_quarter, &block_start_x, &block_start_y);
			color[block_start_x + 1][block_start_y + 1] = block_color;
			color[block_start_x][block_start_y + 1] = block_color;
			color[block_start_x + 1][block_start_y] = block_color;
			color[block_start_x][block_start_y] = block_color;
			if ( block_quarter == 0 ){
				color[block_start_x + 2][block_start_y + 1] = block_color;
				color[block_start_x + 2][block_start_y] = block_color;
				color[block_start_x + 3][block_start_y + 1] = block_color;
				color[block_start_x + 3][block_start_y] = block_color;
			}										
			else{
				color[block_start_x + 1][block_start_y + 3] = block_color;
				color[block_start_x][block_start_y + 3] = block_color;
				color[block_start_x + 1][block_start_y + 2] = block_color;
				color[block_start_x][block_start_y + 2] = block_color;
			}
		}
		if ( solve(start_x, start_y, start_x, start_y) )
			printf("OK\n");
		else
			printf("NG\n");
	}
	return 0;
}

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

bool b;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
int board[105][105];
int w , h , xg , yg , sc;

void dfs(int x , int y){
	if(x==xg&&y==yg) {
		b=true;
		return;
	}
	for(int i=0;i<4;++i){
		int tx=x+dx[i];
		int ty=y+dy[i];
		if(tx<=0 || ty<=0 || tx>w || ty>h || board[tx][ty]!=sc || board[tx][ty]==0 || b ) continue;
		dfs( tx,ty );
	}
}

int main(){
	while(cin >> w >> h , w||h){
		int xs , ys , n;
		b=false;
		memset(board,0,sizeof(board));
		cin >> xs >> ys >> xg >> yg >> n;
		for(int i=0;i<n;++i){
			int c , d , x , y;
			cin >> c >> d >> x >> y;
			if(!d){
				for(int k=y;k<y+2;++k){
					for(int j=x;j<x+4;++j){
						board[j][k]=c;
					}
				}
			} else {
				for(int k=y;k<y+4;++k){
					for(int j=x;j<x+2;++j){
						board[j][k]=c;
					}
				}
			}
		}
		sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {}
		else  dfs( xs , ys );
		cout << ( b ? "OK" : "NG") << endl;
	}
	return 0;
}