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 <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <utility>
#include <sstream>
#include <complex>
#include <fstream>

using namespace std;

#define FOR(i,a,b) for(long long i=(a);i<(b);i++)
#define REP(i,N) for(long long i=0;i<(N);i++)
#define ALL(s) (s).begin(),(s).end()
#define fi first
#define se second

#define PI acos(-1.0)
#define INF 1000000007
#define MOD 1000000007
#define EPS 1e-10
#define MAX_N 100100
#define MAX_M 100100

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<double, double> PD;
typedef pair<string, ll> PS;
typedef vector<ll> V;
typedef pair<P, char> PC;
typedef pair<int, string> PSI;

int w, h, sx, sy, gx, gy;
int n, c, d, x, y;

bool ans;

int table[110][110];
int dis[110][110];

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

void solve(){
	REP(i, 110)REP(j, 110)dis[i][j] = INF;
	dis[sy][sx] = 0;

	queue<P> que;
	que.push(P(sy, sx));

	while (que.size()){
		P p = que.front(); que.pop();

		if (p.first == gy&&p.second == gx){
			ans = 1;
			return;
		}
		REP(i, 4){
			int nx = p.second + dx[i], ny = p.first + dy[i];
			if (nx >= 0 && nx < w&&ny >= 0 && ny < h){
				if (table[ny][nx] == c&&dis[ny][nx] == INF){
					dis[ny][nx] = dis[p.first][p.second] + 1;
					que.push(P(ny, nx));
				}
			}
		}
	}
}

int main(){
	while (cin >> w >> h&&w + h){
		ans = 0;
		REP(i, 110)REP(j, 110){
			table[i][j] = 0;
			dis[i][j] = 0;
		}
		cin >> sx >> sy >> gx >> gy;
		dis[sy][sx] = 1;

		cin >> n;
		REP(i, n){
			cin >> c >> d >> x >> y;
			if (d == 0){
				REP(i, 2){
					REP(j, 4){
						table[y + i][x + j] = c;
					}
				}
			}
			else{
				REP(i, 4){
					REP(j, 2){
						table[y + i][x + j] = c;
					}
				}
			}
		}
		solve();
		if (ans)cout << "OK" << endl;
		else cout << "NG" << endl;
	}
}

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] = -1;
  DFS(Y+1,X  ,c);
  DFS(Y-1  ,X,c);
  DFS(Y,X+1  ,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<105; i++){
      for(int j=0; j<105; 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] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

C++: /* 0207 */
#include <iostream>
using namespace std;
int n,w,h;
int M[101][101];
int sx,sy,ex,ey;

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]=0;
	if(x==ex&&y==ey)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>>sx>>sy>>ex>>ey;
		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;
					}
				}
			}
		}
		// for(int i=1;i<=h;i++){
		// 	for(int j=1;j<=w;j++){
		// 		cout<<M[i][j]<<" ";
		// 	}
		// 	cout<<endl;
		// }
		if((sy==ey&&sx==ex)||walk(sx,sy,M[sx][sy]))cout<<"OK"<<endl;
		else cout<<"NG"<<endl;
		// if(M[c][d]==9)cout<<"OK"<<endl;
		// else cout<<"NG"<<endl;
	}
	return 0;
}