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>
using namespace std;

int f[102][102];

void DFS(int x,int y,int c){
    if(f[x][y]!=c)  return;

    f[x][y]=10;
    DFS(x+1,y,c);
    DFS(x-1,y,c);
    DFS(x,y+1,c);
    DFS(x,y-1,c);
}

void print(int w,int h){
    for(int i=1;i<=w;i++){
        for(int j=1;j<=h;j++){
            cout<<f[i][j]<<' ';
        }
        cout<<endl;
    }
}

int main(){
    int w,h;
    int xs,ys;
    int xg,yg;
    int n;
    while(true){
        cin>>w>>h;
        if(w+h==0)  break;
        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                f[i][j]=-1;
            }
        }
        cin >> xs >> ys;
        cin >> xg >> yg;
        cin >> 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++){
                    for(int k = 0; k<2; k++){
                        f[x+j][y+k] = c;
                    }
                }
            }else{
                for(int j = 0; j<2; j++){
                    for(int k = 0; k<4; k++){
                        f[x+j][y+k] = c;
                    }
                }
            }
        }
        //print(w,h);
        DFS(xs,ys,f[xs][ys]);
        //print(w,h);
        if(f[xg][yg]==10){
            cout<<"OK"<<endl;
        }else{
            cout<<"NG"<<endl;
        }
    }
    return 0;
}

C++: #include <iostream>
using namespace std;
  
int F[102][102];
int xg,yg,w,h;
  
  
void DFS(int Y,int X,int c){
  if(Y < 1 || X < 1)
    //return;
  if(F[Y][X] != c || Y > w || X > h){
    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 xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<102; i++){
      for(int j=0; j<102; j++){
        F[i][j] = 00;
      }
    }
      
    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++: #include<iostream>
#include<cstring>

using namespace std;

int w,h;
int map[101][101];
int xg,yg;

int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
void mapout()
{
  for(int xx=0;xx<h;xx++,cout<<endl)
    for(int yy=0;yy<w;yy++)
      if(map[xx][yy]!=-1)
      cout<<map[xx][yy];
      else
	cout<<"X";
}

bool check(int x,int y)
{
  //  cout<<"check "<<x<<" "<<y<<";"<<map[x][y]<<endl;
  if(x==xg&&y==yg)
    return true;
  int buf=map[x][y];
  map[x][y]=-1;
  for(int i=0;i<4;i++)
    {
      if(x+dx[i]>=0&&x+dx[i]<h&&
	 y+dy[i]>=0&&y+dy[i]<w&&
	 buf==map[x+dx[i]][y+dy[i]] &&
	 map[x+dx[i]][y+dy[i]]!=-1 &&
	 check(x+dx[i],y+dy[i]))
	return true;
    }

  
  return false;
}

int main()
{
  for(;cin>>w>>h,w;)
    {
      memset(map,-1,sizeof(map));
      int xs,ys;
      cin>>xs>>ys;
      cin>>xg>>yg;
      xs--;ys--;
      xg--;yg--;
      
      int n;
      cin>>n;
      for(;n--;)
	{
	  int c,d,x,y;
	  cin>>c>>d>>y>>x;
	  x--;y--;
	  if(d==0)
	    {
	      for(int xx=x;xx<x+2;xx++)
		for(int yy=y;yy<y+4;yy++)
		  map[xx][yy]=c;
	    }
	  else
	    {
	      for(int xx=x;xx<x+4;xx++)
		for(int yy=y;yy<y+2;yy++)
		  map[xx][yy]=c;
	    }
	}
      //   mapout();
      if(check(xs,ys))
	cout<<"OK"<<endl;
      else 
	cout<<"NG"<<endl;
    }
  
  

}

C++: #include <iostream>
using namespace std;
  
int F[105][105];
int xg,yg,w,h;
  
  
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 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] = 10;
      }
    }
      
    cin >> xs >> ys >> xg >> yg >> n;
  
  
    for(int i=0;i<n;i++){
      int c,d,x,y;
      cin >> c >> d >> x >> y;
      if(c == 10)
        c = 2345;
      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++: // 2015/03/25 Tazoe

#include <iostream>
using namespace std;

void DFS(int F[102][102], int y, int x, int C)
{
	if(F[y][x]!=C)
		return;

	F[y][x] = 6;

	DFS(F, y-1, x, C);
	DFS(F, y, x+1, C);
	DFS(F, y+1, x, C);
	DFS(F, y, x-1, C);
}

int main()
{
	while(true){
		int w, h;
		cin >> w >> h;

		if(w==0 && h==0)
			break;

		int xs, ys;
		cin >> xs >> ys;

		int xg, yg;
		cin >> xg >> yg;

		int n;
		cin >> n;

		int F[102][102] = {};

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

			F[y][x] = F[y][x+1] = F[y+1][x] = F[y+1][x+1] = c;

			if(d==0){
				F[y][x+2] = F[y][x+3] = F[y+1][x+2] = F[y+1][x+3] = c;
			}
			else{
				F[y+2][x] = F[y+2][x+1] = F[y+3][x] = F[y+3][x+1] = c;
			}
		}

//		for(int y=0; y<=h; y++){
//			for(int x=0; x<=w; x++){
//				cout << F[y][x];
//			}
//			cout << endl;
//		}

		if(F[ys][xs]==0){
			cout << "NG" << endl;
			continue;
		}

		DFS(F, ys, xs, F[ys][xs]);

		if(F[yg][xg]==6){
			cout << "OK" << endl;
		}
		else{
			cout << "NG" << endl;
		}
	}

	return 0;
}