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;

char F[102][102];
void DFC(int y,int x);
void block_set(int c,int d,int x,int y);
int cs;
int xg,yg;
bool result = false;

int main(){
  int H,W;
  while(1){
    result = false;
    cin >> H >> W;
    if(H==0&&W==0)
      break;
    int xs,ys;
    cin >> xs >> ys >> xg >> yg;
    int n;
    cin >> n;
    int c,d,x,y;
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
      if(i==0)
        cs = c;
        block_set(c,d,x,y);
    }

    DFC(xs,ys);

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

  return 0;
}

void DFC(int x,int y){
  if(F[x][y]!=cs)
    return;

  if(x==xg,y==yg)
    result = true;

  F[x][y]=0;

  DFC(x-1,y);
  DFC(x+1,y);
  DFC(x,y-1);
  DFC(x,y+1);
}

void block_set(int c,int d,int x,int y){
  for(int i=0;i<2;i++){
    for(int j=0;j<4;j++){
      if(d){
        F[x+i][y+j] = c;
      }
      else{
        F[x+j][y+i] = c;
      }
    }
  }
}

C++: #include "bits/stdc++.h"

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> pii;
typedef long long ll;

#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back


int fie[200][200];
int color;
int w,h;
int sx,sy,gx,gy,n;

void dfs(int y,int x){
    int dx[]={1,0,-1,0};
    int dy[]={0,1,0,-1};
    fie[y][x]=9;
    
    rep(i,4){
        if( 0<=x+dx[i] && x+dx[i]<w  &&  0<=y+dy[i] && y+dy[i]<h  &&  fie[ y+dy[i] ][ x+dx[i] ]==color ){
            dfs(y+dy[i],x+dx[i]);
        }
    }
}



int main(){
    while(cin>>w>>h){
        if(w==0&&h==0)break;
        rep(i,200)rep(j,200)fie[i][j]=0;
        
        cin>>sx>>sy>>gx>>gy>>n;
        sx--,sy--,gx--,gy--;
        rep(i,n){
            int c,d,x,y;
            cin>>c>>d>>x>>y;
            x--,y--;
            
            if(d==0){
                int dx[]={0,0,1,1,2,2,3,3};
                int dy[]={0,1,0,1,0,1,0,1};
                rep(i,8) fie[y+dy[i]][x+dx[i]]=c;
            }else{
                int dx[]={0,1,0,1,0,1,0,1};
                int dy[]={0,0,1,1,2,2,3,3};
                rep(i,8) fie[y+dy[i]][x+dx[i]]=c;
            }
        }
        
        color=fie[sy][sx];
        dfs(sy,sx);
        if(fie[gy][gx]==9)cout<<"OK"<<endl;
        else cout<<"NG"<<endl;

    }
}

C++: #include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <list>
#include <iostream>
#include <sstream>
#include <climits>
#include <cfloat>
#include <complex>

using namespace std;

int w, h;
int b[101][101];
int xg, yg;
bool is_reachable(int x, int y, int c)
{
	if (x < 1 || y < 1 || x > w || y > h || b[y][x] != c)
		return false;
	if (x == xg && y == yg)
		return true;
	b[y][x] = -1;
	int dx[] = { 0, 1, 0, -1 };
	int dy[] = { -1, 0, 1, 0 };
	bool res = false;
	for (int i = 0; i < 4 && !res; ++i)
		res = is_reachable(x+dx[i], y+dy[i], c);
	return res;
}
int main()
{
	while (scanf("%d %d", &w, &h), w | h)
	{
		int xs, ys;
		scanf("%d %d %d %d", &xs, &ys, &xg, &yg);
		int n;
		scanf("%d", &n);
		memset(b, -1, sizeof(b));
		for (int i = 0; i < n; ++i)
		{
			int c, d, x, y;
			scanf("%d %d %d %d", &c, &d, &x, &y);
			int w[2][2] = { { 2, 4 }, { 4, 2 } };
			for (int j = 0; j < w[d][0]; ++j)
				for (int k = 0; k < w[d][1]; ++k)
					b[y+j][x+k] = c;
		}
		if (b[ys][xs] != -1 && is_reachable(xs, ys, b[ys][xs]))
			puts("OK");
		else
			puts("NG");
	}

	return 0;
}