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 board[100][100],w,h,xg,yg;
bool f(int y,int x){
	board[y][x] = -1;
	int dy[] = {-1,0,0,1},dx[] = {0,-1,1,0},i;
	if(y == yg - 1 && x == xg -1) return true;
	for(i = 0;i < 4;i++){
		if(y + dy[i] > -1 && y + dy[i] < h && x + dx[i] > -1 && x + dx[i] < w){
			if(board[y+dy[i]][x+dx[i]] == 2){
				if(f(y+dy[i],x+dx[i])) return true;
			}
		}
	}
	return false;
}
int main(){
	int xs,ys,n,i,c,d,x,y,j,k;
	while(cin >> w >> h && (w != 0 && h != 0)){
		cin >> xs >> ys;
		cin >> xg >> yg;
		cin >> n;
		for(i = 0;i < n;i++){
			cin >> c >> d >> x >> y;
			x -= 1;
			y -= 1;
			if(d == 0){
				for(j = 0;j < 2;j++){
					for(k = 0;k < 4;k++){
						board[y+j][x+k] = c;
					}
				}
			}
			else if(d == 1){
				for(j = 0;j < 2;j++){
					for(k = 0;k < 4;k++){
						board[y+k][x+j] = c;
					}
				}
			}
		}
		if(board[ys - 1][xs - 1] == 2){
			if(f(ys - 1,xs -1)) cout << "OK" << endl;
			else cout << "NG" << endl;
		}
		else cout << "NG" << endl;
		for(j = 0;j < 100;j++){
			for(i = 0;i < 100;i++){
				board[j][i] = -1;
			}
		}
	}
	return 0;
}

C++: #include <iostream>
#include <queue>

using namespace std;

int board[102][102];
bool visited[102][102];

int w, h, xg, yg;

class Point{
public:
	int x, y;

	Point(int xx, int yy){
		x = xx;
		y = yy;
	}
};

bool judge(int, int);
int main(void){
	const int UNDEFINED = 0;
	const int BLOCK_WIDTH = 2;
	const int BLOCK_HEIGHT = 4;

	for(int i = 0; i < 102; i ++)
		for(int j = 0; j < 102; j ++){
			board[i][j] = UNDEFINED;
			visited[i][j] = false;
		}	
	for(int xs, ys, n; cin >> w >> h >> xs >> ys >> xg >> yg >> n, w, h;){
		for(int i = 1; i <= w; i ++){
			for(int j = 1; j <= h; j ++){
				board[j][i] = UNDEFINED;
				visited[j][i] = false;
			}
		}

		while(n --){
			int c, d, x, y; cin >> c >> d >> x >> y;
			
			int width = (!d) ? BLOCK_HEIGHT:BLOCK_WIDTH;
			int height = (!d) ? BLOCK_WIDTH:BLOCK_HEIGHT;

			for(int curX = x; curX <= x + width; curX ++)
				for(int curY = y; curY <= y + height; curY ++)
					board[curX][curY] = c;
		}
		cout << ((judge(xs, ys)) ? "OK":"NG") << endl;
	}

	return 0;
}

bool judge(int firstX, int firstY){
	queue<Point> q; Point p(firstX, firstY);
	q.push(p);
	visited[firstY][firstX] = true;

	int targetColor = board[firstY][firstX];
	
	while(!q.empty()){
		if(visited[yg][xg]) return true;
		Point currentNode = q.front(); q.pop();

		for(int delta = -1; delta <= 1; delta += 2){
			for(int a = 0; a < 2; a ++){
				Point nextNode(currentNode.x + ((a)?delta:0), currentNode.y + ((a)?0:delta));

				if(!visited[nextNode.y][nextNode.x] && board[nextNode.y][nextNode.x] == targetColor){
					q.push(nextNode);
					visited[nextNode.y][nextNode.x] = true;
				}
			}
		}
	}

	return false;
}

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

int map[102][102];

void route(int w, int h, int color) {
	if (map[w][h] != color)
		return;
	map[w][h] = 0;
	route(w, h + 1, color);
	route(w + 1, h, color);
	route(w, h - 1, color);
	route(w - 1, h, color);
}


int main() {
	int h, w, xs, ys, xg, yg, n;
	int c, d, x, y,color;

	while (1) {
		cin >> w >> h >> xs >> ys >> xg >> yg >> n;
		if (w == 0 && h == 0)
			break;

		for (int i = 0; i<n; i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				for (int j = 0; j < 4; j++)
					map[j + x][y] = map[j + x][y+1] = c;
			}
			else {
				for (int j = 0; j < 4; j++)
					map[x][y + j] = map[x + 1][y + j] = c;
			}
		}
		color = map[xs][ys];
		route(xs, ys, color);
		if (map[xg][yg]==0)
			cout << "OK" << endl;
		else
			cout << "NG"<<endl;
	}

	return 0;
}

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

int w, h;
vector < vector <int> > block_map;
vector < vector <bool> > visited;

int xs, ys;
int xg, yg;

const int dx[4] = { 1, 0, -1, 0 };
const int dy[4] = { 0, -1, 0, 1 };

int abs( int n )
{
	if ( n < 0 )
		return -n;
	return n;
}

int getMD( int x, int y )
{
	return abs(xg-x) + abs(yg-y);
}

bool dfs( int x, int y, int now, int depth )
{
	if ( x == xg && y == yg )
		return true;
	if ( now + getMD(x,y) > depth )
		return false;

	for ( int i = 0; i < 4; i++ )
	{
		int nx = x + dx[i];
		int ny = y + dy[i];
		if ( nx < 0 || nx >= w || ny < 0 || ny >= h )
			continue;

		if ( visited[ny][nx] == false && block_map[ny][nx] == block_map[ys][xs] )
		{
			visited[ny][nx] = true;
			if ( dfs( nx, ny, now + 1, depth ) )
			{
				return true;
			}
		}
	}

	return false;
}

int main( void )
{
	while ( 1 )
	{
		cin >> w >> h;
		if ( w == 0 && h == 0 )
			break;

		block_map = vector < vector <int> >( h, vector <int>(w,0) );
		visited = vector < vector <bool> >( h, vector <bool>(w,false) );

		cin >> xs >> ys >> xg >> yg;

		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;
			x--;
			y--;

			if ( d == 0 )
			{
				for ( int by = 0; by < 2; by++ )
				{
					for ( int bx = 0; bx < 4; bx++ )
					{
						block_map[y+by][x+bx] = c;
					}
				}
			}
			else
			{
				for ( int by = 0; by < 4; by++ )
				{
					for ( int bx = 0; bx < 2; bx++ )
					{
						block_map[y+by][x+bx] = c;
					}
				}
			}
		}

		visited[ys][xs] = true;
		bool ok_flag = false;
		for ( int i = 0; i < w + h; i++ )
		{
			if ( dfs( xs, ys, 0, i ) )
			{
				ok_flag = true;
				break;
			}
		}
		if ( ok_flag )
			cout << "OK" << endl;
		else
			cout << "NG" << endl;

	}
	return 0;
}