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];
int xg, yg;

bool DFS(int Y, int X, int C)
{
  if(F[Y][X]!=C)
    return false;
  else if(Y == yg && X == xg)
    return true;

  F[Y][X] = 0;

  bool tmp = 0;
  tmp += DFS(Y-1, X, C);
  tmp += DFS(Y+1, X, C);
  tmp += DFS(Y, X-1, C);
  tmp += DFS(Y, X+1, C);
  return tmp;
}

int main()
{
  while(1){
    F[102][102] = {};

    int w=0, h=0;
    cin >> w >> h;

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

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

    cin >> xg >> yg;

    int n;
    cin >> n;

    int c, d, x, y;
    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++)
            F[y+j][x+k] = c;
      else
        for(int j=0; j<4; j++)
          for(int k=0; k<2; k++)
            F[y+j][x+k] = c;
    }

    bool res = DFS(ys, xs, F[ys][xs]);

    if(res)
      cout << "OK" << endl;
    else
      cout << "NG" << endl;
  }
}

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

typedef pair<int,int> P;

int main(){
  int w,h;
  int xs,ys,xg,yg;
  int n;
  int c,d,x,y;
  int grid[101][101];
  bool visit[101][101];

  for(;;){
    cin >> w >> h;
    if(!w && !h)break;

    for(int i=1;i<=h;i++)
      for(int j=1;j<=w;j++){
	grid[i][j] = 0;
	visit[i][j] = false;
      }
    cin >> xs >> ys >> xg >> yg;

    cin >> n;
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
      if(d){
	for(int j=0;j<4;j++)
	  for(int k=0;k<2;k++)grid[y+j][x+k] = c;
      }else{
	for(int j=0;j<2;j++)
	  for(int k=0;k<4;k++)grid[y+j][x+k] = c;
      }
    }
    /*
    for(int i=1;i<=h;i++){
      for(int j=1;j<=w;j++)cout << grid[i][j];
      cout << endl;
    }
    */
    int color = grid[ys][xs];    
    queue<P> q;
    if(color){
      q.push(P(ys,xs));
      
      while(q.size()){
	P p = q.front();q.pop();
	y = p.first;
	x = p.second;
	if(yg == y && xg == x){
	  cout << "OK\n";
	  q.push(P(y,x));
	  break;
	}
	visit[y][x] = true;
	
	int dx[] = {0,1,0,-1},dy[] = {-1,0,1,0};
	for(int i=0;i<4;i++){
	  int sx = x+dx[i],sy = y+dy[i];
	
	  if(sx<0 || sy<0 || w<=sx || h<=sy)continue;
	  
	  if(visit[sy][sx] || grid[sy][sx]!=color)continue;
	  q.push(P(sy,sx));
	}
      }
    }
    if(q.empty())cout << "NG\n";
  }
}

C++: // WA.
#include<iostream>
#include<cstring>
#include<stack>
using namespace std;

int w, h, xs, ys, xg, yg;
int mat[102][102];
int dx[4] = {-1, 0, 0, 1};
int dy[4] = {0, 1, -1, 0};

void init(){
    for(int i = 0; i < 102; i++){
        for(int j = 0; j < 102; j++){
            mat[i][j] = 0;
        }
    }
}

bool bfs(){
    int c = mat[xs][ys];
    stack<pair<int,int>> s;
    s.push({xs,ys});
    bool visit[102][102] = {};
    
    while(!s.empty()){
        pair<int,int> now = s.top(); 
        s.pop();
        
        if(now.first == xg && now.second == yg){
            return true;
        }
        
        visit[now.first][now.second] = true;
        
        for(int i = 0; i < 4; i++){
            int nx = now.first + dx[i];
            int ny = now.second + dy[i];
            
            if(mat[nx][ny] == c && !visit[nx][ny]){
                s.push({nx,ny});
            }
        }
    }
    
    return false;
}


int main(){
    while(1){
        cin >> w >> h;
        cout << w << " " << h << endl;
        if(w + h == 0)  break;
        cin >> xs >> ys >> xg >> yg;
        
        init();
        
        int n;
        cin >> n;
        
        int c, d, x, y;
        while(n-- > 0){
            cin >> c >> d >> x >> y;
            if(d == 0){
                for(int i = 0; i < 2; i++){
                    for(int j = 0; j < 4; j++){
                        mat[x+i][y+j] = c;
                    }
                }
            }else if(d == 1){
                for(int i = 0; i < 4; i++){
                    for(int j = 0; j < 2; j++){
                        mat[x+i][y+j] = c;
                    }
                }
            }
        }
        
        if(bfs())   cout << "OK" << endl;
        else        cout << "NG" << endl;
    }
    return 0;
}