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++: 
//インクルード文
#include <iostream>
#include <stack>
#include <vector>
#include <stdlib.h>
#include <cstdio>
#include <string>
//#include <assert.h>

//:std省略
using namespace std;

//グローバル変数
int f[1000][1000];

//マクロ指定
#define fc f[x + j][y + l] = c

//深さ優先探索( dfs = Depth - First Search )
void dfs(int a, int b, int c) {

	if (f[a][b] == c) {


		f[a][b] = 10;
		dfs(a + 1, b, c);
		dfs(a - 1, b, c);
		dfs(a, b + 1, c);
		dfs(a, b - 1, c);


	}

//	else return;

}

//メイン文
int main(){

	int w, h, n = 0;
	int i, j, l;
	int xs, ys; 
	int xg, yg;

	const int cnt = w + h;

	while(true) {
		cin >> w >> h;

		
		if ( cnt == 0) break;
		
		for (i = 1; i <= h; ++i) {
			for (j = 1; j <= w; ++j) {
				f[i][j] = -1;
			}
		}

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

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

			cin >> c >> d;
			cin >> x >> y;

			if (d == 0) {
				for (j = 0; j < 4; ++j) {
					for (l = 0; l < 2; ++l) {
						fc;
					}
				}
			}

			else {//d==1

				

				for (j = 0; j < 2; ++j) {
					for (l= 0; l < 4; ++l) {
						fc;
					}
				}
			}
		}
/*

			if (d == 0) {
				for (j = 0; j < 2; ++j) {
					for (l = 0; l < 4; ++l) {
						f[x + j][y + l] = c;
					}
				}
			}

			else {
				for (j = 0; j < 4; ++j) {
					for (l= 0; l < 2; ++l) {
						f[x + j][y + l] = c;
					}
				}
			}	
		}

*/


		dfs(xs, ys, f[xs][ys]);


//		char gg = 'OK';
//		char ggwp = 'NG';


		

		if (f[xg][yg] == 10) printf("OK\n");

		else 		         printf("NG\n");



			//			assert(i == 10);
			//			assert(i = 9);
			//			assert(i = 8);
			//			assert(i = 7);
			//			assert(i = 6);
			//			assert(i = 5);
			//			assert(i = 4);
			//			assert(i = 3);
			//			assert(i = 2);
			//			assert(i = 1);

		


	}
	return 0;
}

/*


20 20
1 1
9 9
7
2 0 1 1
5 1 1 3
2 1 3 3
1 1 5 2
5 1 7 3
2 0 2 7
2 0 6 8
20 20
9 9
1 1
6
2 0 1 1
1 0 5 1
2 1 1 3
5 0 1 7
3 1 5 5
4 1 8 5
0 0


*/

C++: #include <iostream>
using namespace std;
 
int F[105][105];
int xg,yg;
 
 
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
 
  F[Y][X] = -2;
  DFS(Y-1,X  ,c);
  DFS(Y  ,X+1,c);
  DFS(Y+1,X  ,c);
  DFS(Y  ,X-1,c);
}
 
 
int main(){
  int w,h,xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<20; i++){
      for(int j=0; j<20; j++){
        F[i][j]=0;
      }
    }
     
    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 == 0){
        for(int j=0;j<4;j++){
          F[x+j][y] = c;
          F[x+j][y+1] = c;
        }
      } else {
        for(int j=0;j<4;j++){
          F[x][y+j] = c;
          F[x+1][y+j] = c;
        }
      }
    }

  DFS(xs,ys,F[xs][ys]);
 
  if(F[xg][yg] == -2){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

C++: #include<iostream>

using namespace std;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int N;
int W,H;
pair<int,int>s;
pair<int,int>g;
int sc;
int map[103][103]={0};
bool flag[103][103]={0};
int ans=0;

bool se(int x,int y){
	if(x==g.first && y==g.second)ans=1;
	for(int i=0;i<4;i++){
		int xx=x+dx[i];
		int yy=dy[i]+y;
		if(xx>=0 &&yy>=0 &&xx<W &&yy<H && sc==map[xx][yy]&& flag[xx][yy]==0){
			flag[xx][yy]=1;
			se(xx,yy);
		}
	}
	return 0;
}


int main(){
	
	while(cin>>W>>H>>s.first>>s.second>>g.first>>g.second>>N && W && H){
		int d,c,x,y;
		
		for(int i=0;i<N;i++){
			cin>>c>>d>>x>>y;
			if(d){
				for(int i=x;i<x+2;i++){
					for(int j=y;j<y+4;j++){
						map[i][j]=c;
				}
			}
		}else{
			for(int i=x;i<x+4;i++){
				for(int j=y;j<y+2;j++){
					map[i][j]=c;
				}
			}
		}
		}
		sc=map[s.first][s.second];
		flag[s.first][s.second]=1;
		se(s.first,s.second);
		if(ans)cout<<"OK"<<endl;
		else cout<<"NG"<<endl;
		//if(se(s.first,s.second))cout<<"OK"<<endl;
		//else cout<<"NG"<<endl;

	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int h,w,a[100][100];
int d1[]={0,0,1,-1},d2[]={1,-1,0,0};
void dfs(int y,int x,int c){
  a[y][x]=0;
  for(int i=0;i<4;i++){
    int yy=d2[i]+y,xx=d1[i]+x;
    if(yy>=0&&xx>=0&&xx<w&&yy<h)
      if(a[yy][xx]==c)
        dfs(yy,xx,c);
  }
}
int main(){
  while(cin>>w>>h,h){
    memset(a,0,sizeof(a));
    int sx,sy,gx,gy;
    cin>>sx>>sy>>gx>>gy;
    sx--;sy--;gx--;gy--;
    int m;
    cin>>m;
    while(m--){
      int q,w,e,r;
      cin>>q>>w>>e>>r;
      w;e--;r--;
      int dy[2][8] = {{0,0,0,0,1,1,1,1},{0,0,1,1,2,2,3,3}}, dx[2][8] = {{0,1,2,3,0,1,2,3},{0,1,0,1,0,1,0,1}};
      for(int i=0;i<8;i++)
        a[r+dy[w][i]][e+dx[w][i]]=q;
    }
    if(a[sy][sx]!=0&&a[gy][gx]==a[sy][sx]){
      dfs(sy,sx,a[sy][sx]);
      if(a[gy][gx]==0)cout<<"OK"<<endl;
      else goto L;
    }
    else{L:;
      cout<<"NG"<<endl;
    }
  }
}