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

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 <= board_range_w + 1; i++ ){
			for ( int j = 0; j <= board_range_h + 1; 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++ ){
			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 ){
				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) ) 
			printf("OK\n");
		else
			printf("NG\n");
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<string>
using namespace std;
int w,h,xs,ys,xg,yg,n,ban[111][111]={{0},{0}};
bool visited [101][101];
const int START=4545191;
const int GOAL=454545;

	bool dfs(int x,int y){
		//cout<<x<<" "<<y<<endl;
		if(xg==x&&yg==y)return true;
		
		if(ban[x+1][y]==ban[xs][ys]&&visited[x][y]==false){
			visited[x][y]=true;
			if(dfs(x+1,y))return true;
		}
		if(ban[x][y+1]==ban[xs][ys]&&visited[x][y]==false){
			visited[x][y]=true;
			if(dfs(x,y+1))return true;
		}
		if(x>=2&&ban[x-1][y]==ban[xs][y]){
			if(dfs(x-1,y))return true;
		}
		if(y>=2&&ban[x][y-1]==ban[xs][y]){
			if(dfs(x,y-1))return true;
		}
		return false;
	}


int main(){

	while(cin>>w>>h&&w&&h){
	cin>>xs>>ys>>xg>>yg>>n;
	for(int i=0;i<101;i++)
	for(int j=0;j<101;j++)ban[i][j]=0,visited[i][j]=false;
	
	for(int i=0;i<n;i++){
		int c,d,x,y;
		cin>>c>>d>>x>>y;
		if(!d){
			for(int i=x;i<x+4;i++){
				for(int j=y;j<y+2;j++){
					ban[i][j]=c;
				}
			}
		}
		else{
		for(int i=x;i<x+2;i++){
				for(int j=y;j<y+4;j++){
					ban[i][j]=c;
				}
			}
		}
	}
	
	if(dfs(xs,ys))cout<<"OK"<<endl;
	else cout<<"NG"<<endl;
	}
	return 0;
	}

C++: #include "stdafx.h"
#include <iostream>
using namespace std;

int F[102][102];

void DFS(int Y, int X, int c) {
	//cout << Y << " " << X << endl;
	if (F[Y][X] != c || c != 0)
		return;
	F[Y][X] = 10;
	DFS(Y - 1, X, c);//???
					 //DFS(Y - 1, X+1, A_ito);//??????
	DFS(Y, X + 1, c);//???
					 //DFS(Y + 1, X+1, A_ito);//??????
	DFS(Y + 1, X, c);//???
					 //DFS(Y + 1, X-1, A_ito);//??????
	DFS(Y, X - 1, c);//???
					 //DFS(Y - 1, X-1, A_ito);//??????
}


int main()
{
	int xs, ys, xg, yg, n;
	int c, d, x, y;
	int W = 1, H = 1;

	while ((W != 0) && (H != 0)) {
		cin >> W >> H;
		cin >> xs >> ys >> xg >> yg >> n;
		for (int i = 1;i <= n;i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				F[x][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y] = c;
				F[x + 1][y + 1] = c;
				F[x + 2][y] = c;
				F[x + 2][y + 1] = c;
				F[x + 3][y] = c;
				F[x + 3][y + 1] = c;
			}
			if (d == 1) {
				F[x][y] = c;
				F[x + 1][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y + 1] = c;
				F[x][y + 2] = c;
				F[x + 1][y + 2] = c;
				F[x][y + 3] = c;
				F[x + 1][y + 3] = c;
			}
		}
		if (F[ys][xs] != 0)
			DFS(ys, xs, F[ys][xs]);

		if (F[yg][xg] == 10) {
			cout << "OK" << endl;
		}
		else { cout << "NG" << endl; }
		/*for (int i = 0;i < H;i++) {
			for (int j = 0;j < W;j++) {
				F[i][j] = 0;
			}
		}
		*/
	}

	return 0;
}