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<stdio.h>
#include<iostream>
#include<list>
#include<map>
#include<vector>
#include<algorithm>
#include<string.h>
#define range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) range(i,0,b)
#define debug(x) cout << x << endl;
using namespace std;

int xstart, ystart;
int xgoal, ygoal;
int load;
bool check;

int answer(int maze[][1000], int x, int y){
    if(load == maze[x][y]){
        maze[x][y] = 0;
    }else{
        return 0;
    }
    if(x == xgoal && y == ygoal){
        cout << "OK" << endl;
        check = true;
        return 1;
    }
    answer(maze, x+1,y);
    answer(maze, x,y+1);
    answer(maze, x,y-1);
    answer(maze, x-1,y);
}

int main(){
    int width, height;
    int n;
    int color, direction, x, y;

    while(cin >> width >> height, height){
        int maze[1000][1000];
        check = false;
        cin >> xstart >> ystart >> xgoal >> ygoal >> n;
        rep(i,n){
            cin >> color >> direction >> x >> y;
            if(direction == 0){
                maze[x][y] = color;
                maze[x+1][y] = color;
                maze[x+2][y] = color;
                maze[x+3][y] = color;
                maze[x][y+1] = color;
                maze[x+1][y+1] = color;
                maze[x+2][y+1] = color;
                maze[x+3][y+1] = color;
            }else{
                maze[x][y] = color;
                maze[x][y+1] = color;
                maze[x][y+2] = color;
                maze[x][y+3] = color;
                maze[x+1][y+1] = color;
                maze[x+1][y+2] = color;
                maze[x+1][y+3] = color;
                maze[x+1][y+4] = color;
            }
        }
        load = maze[xstart][ystart];
        answer(maze, xstart, ystart);
        if(check == false){
            cout << "NG" << endl;
        }
    }
}

C++: #include<iostream>
using namespace std;
int w,h,xs,ys,xg,yg,n;
int map[101][101];
string ans;
void fun(int y,int x){
    if(map[y][x]==map[ys][xs]){
        map[y][x]=7;
    }
    else
        return;
    if(x<1||w<x||y<1||h<y)
        return;
    if(map[y+1][x+1]==map[yg][xg]){
        ans="OK";
        return;
    }
    fun(y,x+2);
    fun(y,x-2);
    fun(y+2,x);
    fun(y-2,x);
}
void mc(){
    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++){
                    map[y+j][x+k]=c;
                }
            }
        }
        else{
            for(int j=0;j<4;j++){
                for(int k=0;k<2;k++){
                    map[y+j][x+k]=c;
                }
            }
        }
    }
}
int main(){
    while(cin >> w >> h,w){
    	ans="NG";
        cin >> xs >> ys >> xg >> yg >> n;
        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                map[i][j]=0;
            }
        }
        mc();
        if(map[ys][xs]==0||map[yg][xg]==0);
        else
        	fun(ys,xs);
        for(int i=1;i<w;i++){
        	for(int j=1;j<h;j++){
        		cout << map[i][j];
        	}
        	cout << endl;
        }
        cout << ans << endl;
    }
}

C++: #include <cstdio>
#include <cstring>
#include <vector>
#include <map>
#include <algorithm>

#define rep(i, j) FOR(i, 0, j)
#define FOR(i, j, k) for(int i = j; i < k; ++i)

using namespace std;

int w, h, xs, ys, xg, yg, n, c, d, x, y, b[101][101];
int dx[] = {0, -1, 0, 1}, dy[] = {-1, 0, 1, 0};

bool dfs(int x, int y){
  int nx, ny;
  b[x][y] = 0;
  if(x == xg && y == yg) return true;
  bool r = 0;
  rep(i, 4){
    nx = x + dx[i]; ny = y + dy[i];
    if(nx >= 0 && nx < h && ny >= 0 && ny < w && b[nx][ny]==c)r=r||dfs(nx, ny);
  }
  return r;
}

int main(){
  while(scanf("%d %d", &w, &h) && w && h){
    memset(b, 0, sizeof(b));
    scanf("%d%d%d%d", &ys, &xs, &yg, &xg);
    scanf("%d", &n);
    rep(i, n){
      scanf("%d%d%d%d", &c, &d, &y, &x);
      rep(j, (d>0?4:2)) rep(k, (d>0?2:4)) b[x + j][y + k] = c;
    }

    c = b[xs][ys];
    if(dfs(xs, ys)) puts("OK");
    else puts("NG");
  }
  return 0;
}