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<cstdio>
#include<cstring>
#include<queue>
using namespace std;

#define size_max 100+10

#define Y first
#define X second

int mx[4] = { 1,-1,0,0 };
int my[4] = { 0,0,1,-1 };

int map[size_max][size_max];


void paint(int c, int y, int x, int H, int W)
{
	int i, j;
	for (i = y; i < y + H; i++)
	{
		for (j = x; j < x + W; j++)
		{
			map[i][j] = c;
		}
	}
}


void chek(int w, int h)
{
	int i, j;
	for (i = 0; i <= h + 1; i++)
	{
		for (j = 0; j <= w + 1; j++)
		{
			cout << map[i][j];
		}
		cout << endl;
	}
}


typedef pair<int, int> PR;

int main(void)
{
	PR now, tmp;
	queue<PR> QU;

	int w, h;
	int xs, ys, xg, yg, n;
	int c, d, set_x, set_y;

	int i, j;

	while ((cin >> w >> h), w != 0 && h != 0)
	{
		memset(map, 0, sizeof map);

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

		for (i = 0; i < n; i++)
		{
			cin >> c >> d >> set_x >> set_y;

			if (d == 0)
			{
				paint(c, set_y, set_x, 2, 4);
			}
			else
			{
				paint(c, set_y, set_x, 4, 2);
			}
		}

		//chek(w, h);

		if (map[ys][xs] == 0)
		{
			cout << "NG\n";
			continue;
		}

		now = make_pair(ys, xs);
		QU.push(now);

		bool goal = false;
		while (!QU.empty())
		{
			now = QU.front();
			QU.pop();

			if (map[now.Y][now.X] != -1)
			{
				map[now.Y][now.X] = -1;

				if (now.Y == yg && now.X == xg)
				{
					goal = true;
					while (!QU.empty())
					{
						QU.pop();
					}
					break;
				}

				for (i = 0; i < 4; i++)
				{
					if (map[now.Y + my[i]][now.X + mx[i]] == c)
					{
						tmp = make_pair(now.Y + my[i], now.X + mx[i]);
						QU.push(tmp);
					}
				}
			}
		}

		if (goal)
		{
			cout << "OK\n";
		}
		else
		{
			cout << "NG\n";
		}

	}

	return 0;
}

C++: #include <iostream>
using namespace std;
int F[102][102];

void DFScolor(int X,int Y,int color,int Xg,int Yg){

	if(F[X][Y]!=color)
		return;
	
	F[X][Y]=0;
	DFScolor(X-1,Y,color,Xg,Yg);
	DFScolor(X,Y+1,color,Xg,Yg);
	DFScolor(X+1,Y,color,Xg,Yg);
	DFScolor(X,Y-1,color,Xg,Yg);
	
}


int main(){
while(1){
	int H,W,xg,yg,xs,ys,n;
	cin>>H;
	cin>>W;
	if(H==0&&W==0)
		return 0;
	cin>>xs>>ys;
	cin>>xg>>yg;	
	cin>>n;
	int c,d,x,y;
	int xb[n],yb[n],colo[n];
	for(int i=0;i<n;i++){
		
		cin>>c>>d>>x>>y;
		colo[i]=c;
		xb[i]=x;
		yb[i]=y;
		if(d==0){
			for(int o=y;o<y+2;o++){
				for(int j=x;j<x+4;j++){
					F[j][o]=c;
				}
			}
		}
		else if(d==1){
			for(int o=y;o<y+4;o++){
				for(int j=x;j<x+2;j++){
					F[j][o]=c;
				}
			}
		}
		
	}
	
	for(int i=0;i<n;i++){
		if(xb[i]==xs&&yb[i]==ys){
			DFScolor(xb[i],yb[i],colo[i],xg,yg);
			break;
		}
	}
	if(F[xg][yg]==0)
		cout<<"OK"<<endl;
	if(F[xg][yg]!=0)
		cout<<"NG"<<endl;
	
}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <cassert>
#include <cctype>
#include <complex>
#include <cstdio>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

int show=0;
int w,h,sx,sy,gx,gy,d[101][101],dx[4]={1,0,-1,0},dy[4]={0,1,0,-1},C;
int field[101][101];
const int INF=9999999;
typedef pair<int,int> P;

void bfs(){
	queue<P> que;
	for(int i=1;i<=h;i++)for(int j=1;j<=w;j++)d[i][j]=INF;
	que.push(P(sy,sx));
	d[sy][sx]=0;
	while(!que.empty()){
		P p=que.front(); que.pop();
		if(p.first==gy&&p.second==gx)break;
		for(int i=0;i<4;i++){
			int ny=p.first+dx[i],nx=p.second+dy[i];
			if(1<=ny&&ny<=h&&1<=nx&&nx<=w&&field[ny][nx]==C&&d[ny][nx]==INF){
			que.push(P(ny,nx));
			d[ny][nx]=d[p.first][p.second]+1;
			}
		}
	}
	if(d[gy][gx]==INF)cout<<"NG"<<endl;
	else cout<<"OK"<<endl;
}

int main() {
	while(cin>>h>>w){
		if(!h)return 0;
		int n,c,di,x,y;
		cin>>sx>>sy>>gx>>gy>>n;
		for(int i=1;i<=h;i++)for(int j=1;j<=w;j++)field[i][j]=0;
		for(int i=0;i<n;i++){
			cin>>c>>di>>x>>y;
			for(int j=y;j<y+2+di*2;j++)for(int k=x;k<x+2+!di*2;k++)field[j][k]=c;
		}
		C=field[1][1];
		bfs();
		if(show)for(int i=1;i<=h;i++){for(int j=1;j<=w;j++){if(field[i][j])cout<<field[i][j];else cout<<" ";}cout<<endl;}
	}
}

C++: #include<iostream>
#include<algorithm>
#include<string>
using namespace std;
int w,h,xs,ys,xg,yg,n,ban[111][111]={{0},{0}};
const int START=4545191;
const int GOAL=454545;
const int CHECKED=432535;

	bool dfs(int x,int y,int c){
		//cout<<x<<" "<<y<<endl;
		if(ban[x][y+1]==CHECKED&&ban[x+1][y]==CHECKED)return false;
		if(xg==x&&yg==y)return true;
		if(ban[x+1][y]==c){
			ban[x+1][y]=CHECKED;
			if(dfs(x+1,y,c))return true;
		}
		if(ban[x][y+1]==c){
			ban[x][y+1]=CHECKED;
			if(dfs(x,y+1,c))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;
	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,ban[xs][ys]))cout<<"OK"<<endl;
	else cout<<"NG"<<endl;
	}
	return 0;
	}