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<map>
#include<queue>
#include<cstdio>
#include<cstring>
#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#define SIZE 102
using namespace std;

typedef pair<int,int> P;

void input_data(void);  //データ入力用関数
void make_mass(void);   //マス作成用関数
void solve(void);       //処理
void clear(void);       //データの初期化

int n;             //ブロックの個数
int w,h;           //ボードの幅、高さ
int goal=0;        //迷路になっているか
int scolor;        //スタート位置の色
int sx,sy,gx,gy;   //スタートの座標、ゴールの座標
int mass[SIZE][SIZE];
int data[SIZE][SIZE];
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int c[SIZE],d[SIZE],x[SIZE],y[SIZE];       //ブロックの色、向き、左上の座標


int main(){

  int i,j;             //カウンタ変数

  while(1){

 memset(mass,0,sizeof(mass));
    /*情報の入力*/
    cin>>w>>h;

    if(w==h && w==0)break; //ループ終了条件

    input_data();

    make_mass();

    solve();
    if(scolor!=0 && mass[sy][sx]==mass[gy][gx]){
    if(goal==1){
      cout<<"OK"<<endl;
    } else {
      cout<<"NG"<<endl;
      }
    }
    else {
      cout<<"NG"<<endl;
    }

    clear();
  }

  return 0;
}
void input_data(void){

    cin>>sx>>sy;
    cin>>gx>>gy;

    cin>>n;

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

    }

    return;
}
void make_mass(void){

  int i,j;

    /*マスの作成*/
    for(i=0;i<n;i++){
	switch(d[i]){
	case 0:              //横向きなら
	  for(j=0;j<4;j++){
	    mass[y[i]][x[i]+j]=c[i];
	    mass[y[i]+1][x[i]+j]=c[i];
	  }
	  break;
	case 1:              //縦向きなら
	  for(j=0;j<4;j++){
	    mass[y[i]+j][x[i]]=c[i];
	    mass[y[i]+j][x[i]+1]=c[i];
	  }
	  break;
	}
      }

    scolor=mass[sy][sx];

    for(i=0;i<h;i++){
      for(j=0;j<w;j++){
	if(scolor!=mass[i][j]){
	  mass[i][j]=0;
	}
      }
    }
    
    return;
}
void solve(void){

  int i,j;
  queue<P> que;
  memset(data,-1,sizeof(data));
  que.push(P(sx,sy));     //queにスタート位置の座標を格納
  data[sy][sx]==0;

  while(!que.empty()){    //queが空でない間
    P p=que.front();
    que.pop();

    if(p.first==gx && p.second==gy){
      goal=1;
      /* cout<<" (^q^)くおえうえーーーるえうおおおwwww"<<endl;*/
      break;
    }
    for(i=0;i<4;i++){
      int nx=p.first+dx[i];
      int ny=p.second+dy[i];
      if(nx>=0 && nx<w && ny>=0 && ny<h && mass[ny][nx]!=0 && data[ny][nx]==-1){
	que.push(P(nx,ny));
	data[ny][nx]=1;
      }
    }
  }
  return;
}
void clear(){
  goal=0;
}
/*
花火は他人に向けちゃダメだよ。

( ・ω・)o─━・*:・:・(※)`Д´)アヂィ!

*/

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstdio>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define it ::iterator
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double ESP=1e-10;
using namespace std;
int sx,sy,gx,gy,col;
bool func(vector<vector<int> >out,vector<vector<bool> >&out2,int x,int y){
  out2[x][y]=true;
  rep(i,3)rep(j,3){
    if(out2[x+i][y+j]!=true&&out[x+i][y+j]==col)func(out,out2,x+i,y+j);
  }
}
int main(){
  int n,m;
  while(cin>>m>>n,n|m){
    cin>>sx>>sy>>gx>>gy;
    int nn;cin>>nn;
    vector<vector<int> >out(n+2);
    vector<vector<bool> >out2(n+2);
    rep(i,n+2)rep(j,m+2)out[i].pb(0);
    rep(i,n+2)rep(j,m+2)out2[i].pb(false);
    rep(q,nn){
      int a,b,c,d;
      cin>>a>>b>>d>>c;
      if(b)rep(i,4)rep(j,2)out[i+c][j+d]=a;
      else rep(i,2)rep(j,4)out[i+c][j+d]=a;
    }
    /*cout<<endl;
    rep(i,n){
      rep(j,m)cout<<" "<<out[i+1][j+1];
      cout<<endl;
      }*/
    
    if(out[gx][gy]==0||out[gx][gy]!=out[sx][sy]){
      cout<<"NG"<<endl;
      continue;
    }
    col=out[sx][sy];
    func(out,out2,sx,sy);
    if(out2[gx][gy])cout<<"OK"<<endl;
    else cout<<"NG"<<endl;
    /*rep(i,n){
      rep(j,m)cout<<" "<<out[i+1][j+1];
      cout<<endl;
      }*/
  }
}

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

int F[102][102];
int xg,yg;
int flag = 0;

void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
  if(Y == xg && X == yg){
    flag = 1;
  }

  F[Y][X] = 0;
  DFS(Y-1,X  ,c);
  //DFS(Y-1,X+1,c);
  DFS(Y  ,X+1,c);
  //DFS(Y+1,X+1,c);
  DFS(Y+1,X  ,c);
  //DFS(Y+1,X-1,c);
  DFS(Y  ,X-1,c);
  //DFS(Y-1,X-1,c);
}


int main(){
  int w,h,xs,ys,n;
  while(1){
  cin >> w >> h;
  if(w == 0 && h == 0)
    break;

  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(flag == 1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
}
return 0;
}

C++: #include<iostream>
using namespace std;
int w, h, xs, ys, xg, yg, stage[101][101];
int ny[4] = { 0, 1, 0, -1 }, nx[4] = { 1, 0, -1, 0 };
int bc;
bool ans = false;
void func(int x, int y, int lastp){
	if (x == xg && y == yg){
		ans = true;
	}
	for (int i = 0; i < 4; i++){
		if (stage[y + ny[i]][x + nx[i]] != bc || i == lastp) return;
		func(x + nx[i], y + ny[i], (i + 2) % 4);
	}
}
int main(){
	int n, c, d, x, y, bw, bh;
	while (1){
		for (int i = 0; i < 101; i++){
			for (int j = 0; j < 101; j++){
				stage[i][j] = 0;
			}
		}
		cin >> w >> h;
		if (w == 0 && h == 0) return 0;
		cin >> xs >> ys >> xg >> yg >> n;
		for (int i = 0; i < n; i++){
			cin >> c >> d >> x >> y;
			if (d == 0){
				bw = 4;
				bh = 2;
			}
			else{
				bw = 2;
				bh = 4;
			}
			for (int j = 0; j < bh; j++){
				for (int k = 0; k < bw; k++){
					stage[y + j][x + k] = c;
				}
			}
		}
		bc = stage[ys][xs];
		if (bc == 0){
			cout << "NG\n";
			continue;
		}
		func(1, 1, -1);
		if (ans == true) cout << "OK\n";
		else cout << "NG\n";
	}
	return 0;
}