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++: /* 0207 */
#include <iostream>
using namespace std;
int n,w,h;
int M[101][101];
int a,b,c,d;

int walk(int x,int y,int color){
	if(x<1||w<x||y<1||h<y)return 0;
	if(color!=M[x][y]||color==0)return 0;
	M[x][y]=9;
	if(x==c&&y==d)return 1;
	if(walk(x+1,y,color)||
			walk(x-1,y,color)||
			walk(x,y+1,color)||
			walk(x,y-1,color))return 1;
	return 0;
}
int main(void){
	while(cin>>w>>h,w||h){
		cin>>a>>b>>c>>d;
		for(int i=1;i<=h;i++){
			for(int j=1;j<=w;j++){
				M[i][j]=0;
			}
		}
		int k;
		cin>>k;
		for(int i=0;i<k;i++){
			int w,x,y,z;
			cin>>w>>x>>y>>z;
			if(x){
				for(int Y=z;Y<z+4;Y++){
					for(int X=y;X<y+2;X++){
						M[Y][X]=w;
					}
				}
			}else{
				for(int Y=z;Y<z+2;Y++){
					for(int X=y;X<y+4;X++){
						M[Y][X]=w;
					}
				}
			}
		}
		if(walk(a,b,M[a][b]))cout<<"OK"<<endl;
		else cout<<"NG"<<endl;
		// if(M[c][d]==9)cout<<"OK"<<endl;
		// else cout<<"NG"<<endl;
	}
	return 0;
}

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

using namespace std;

vector < vector<int> > hyou(102, vector<int>(102));

void check(int x, int y, int c) {
	int mx[] = {1, 0, -1, 0};
	int my[] = {0, 1, 0, -1};
	for (int i = 0; i < 4; i++) {
		if (hyou[x+mx[i]][y+my[i]] == c) {
			hyou[x+mx[i]][y+my[i]] = 0;
			check(x+mx[i], y+my[i], c);
		}
	}
}

int main() {
	int w, h;
	while (cin >> w >> h) {
		if (w == 0 && h == 0) {
			break;
		}
		for (int i = 0; i < 102; i++) {
			for (int j = 0; j < 102; j++) {
				hyou[i][j] = 0;
			}
		}
		int xs, ys, xg, yg, n;
		int c, d, x, y;
		cin >> xs >> ys >> xg >> yg >> n;
		for (int i = 0; i < n; i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				for (int j = 0; j < 2; j++) {
					for (int k = 0; k < 4; k++) {
						hyou[x+k][y+j] = c;
					}
				}
			} else {
				for (int j = 0; j < 4; j++) {
					for (int k = 0; k < 2; k++) {
						hyou[x+k][y+j] = c;
					}
				}
			}
		}
		if (hyou[xg][yg] != 0 && hyou[xg][yg] == hyou[xs][ys]) {
			check(xs, ys, hyou[xs][ys]);
			if (hyou[xg][yg] == 0) {
				cout << "OK" << endl;
			} else {
				cout << "NG" << endl;
			}
		} else {
			cout << "NG" << endl;
		}
	}
	return 0;
}

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

using namespace std;

bool saiki( char stage[101][101], int xs, int ys, int xg, int yg, int w, int h, bool data[101][101] )
{
	data[xs][ys] = true;
	if( xs == xg && ys == yg ) return true;
	if( xs + 1 <= w && stage[xs + 1][ys] == stage[xs][ys] && data[xs + 1][ys] == false )if( saiki( stage, xs + 1, ys, xg, yg, w, h, data ) ) return true;
	if( xs - 1 >= 1 && stage[xs - 1][ys] == stage[xs][ys] && data[xs - 1][ys] == false ) if( saiki( stage, xs - 1, ys, xg, yg, w, h, data ) ) return true;
	if( ys + 1 <= h && stage[xs][ys + 1] == stage[xs][ys] && data[xs][ys + 1] == false ) if( saiki( stage, xs, ys + 1, xg, yg, w, h, data ) ) return true;
	if( ys - 1 >= 1 && stage[xs][ys - 1] == stage[xs][ys] && data[xs][ys - 1] == false ) if( saiki( stage, xs, ys - 1, xg, yg, w, h, data  ) ) return true;

	return false;
}


int main(int argc, char const* argv[])
{
	char stage[101][101];
	bool data[101][101];
	int w,h;
	int xs,ys;
	int xg,yg;
	int n;

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

		for( int i = 0;i < 101;i++ ){
			for( int j = 0;j < 101;j++ ){
				stage[i][j] = 0;
				data[i][j] = false;
			}
		}

		for( int i = 0;i < n;i++ ){
			int c,d,x,y;
			cin >> c >> d >> x >> y;

			if( d == 0 ){
				for( int j = 0;j < 2;j++ ){
					for( int k = 0;k < 4;k++ ){
						stage[k + x][j + y] = c;
					}
				}
			} else if( d == 1 ){
				for( int j = 0;j < 4;j++ ){
					for( int k = 0;k < 2;k++ ){
						stage[k + x][j + y] = c;
					}
				}
			}
		}
		if( saiki( stage, xs, ys, xg, yg, w, h ,data ) ) cout << "OK" << endl;
		else cout << "NG" << endl;
	}

	return 0;
}

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

struct board{
  int mass[102][102];
};

bool goal_flag;
void DFS(int x,int y,int gx,int gy,board b,int c){
    if(b.mass[y][x]!=c)return;
    if(!b.mass[y][x])return;
    b.mass[y][x]=-1;
    if(x==gx&&y==gy)goal_flag=true;
    DFS(x+1,y,gx,gy,b,c);
    DFS(x-1,y,gx,gy,b,c);
    DFS(x,y+1,gx,gy,b,c);
    DFS(x,y-1,gx,gy,b,c);
}

int main(){
  int h,w;
  int start_x,start_y;
  int goal_x,goal_y;
  int n;
  int c,d,x,y;
  while(1){
    cin>>w>>h;
    if(w==0&&h==0)break;
    cin>>start_x>>start_y;
    cin>>goal_x>>goal_y;
    cin>>n;

    board b;
    for(int i=0;i<h+2;i++){
      for(int j=0;j<w+2;j++){
        b.mass[i][j]=0;
      }
    }

    for(int i=0;i<n;i++){
        cin>>c>>d>>x>>y;
        for(int j=0;j<2;j++){
          for(int k=0;k<4;k++){
            if(d==0){b.mass[y+j][x+k]=c;}
            else if(d==1){b.mass[y+k][x+j]=c;}
          }
        }
    }
    goal_flag=false;
    DFS(start_x,start_y,goal_x,goal_y,b,b.mass[start_y][start_x]);
    if(goal_flag)cout<<"OK";
    else cout<<"NG";
    cout<<endl;
  }
}