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++: #define _USE_MATH_DEFINES
#include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<climits>
#include<map>
#include<string>
using namespace std;

const int dy[4] = {-1, 0, 1, 0}, dx[4] = {0, 1, 0, -1};

struct Data{
	int y, x;
	Data(){}
	Data(int _y, int _x){
		y = _y; x = _x;
	}
};

int fld[100][100];

void PaintFld(int c, int y, int x, int h, int w){
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			fld[y+i][x+j] = c;
		}
	}
}

int main(){
	int W, H;
	while(cin >> W >> H, W || H){
		fill_n( (int*)fld, 100*100, 0 );
		int Xs, Ys, Xg, Yg, N, C, D, X, Y;
		cin >> Xs >> Ys >> Xg >> Yg >> N;
		Xs--; Ys--; Xg--; Yg--;
		for(int i = 0; i < N; i++){
			cin >> C >> D >> X >> Y;
			X--; Y--;
			if(D == 0) PaintFld(C, Y, X, 2, 4);
			else PaintFld(C, Y, X, 4, 2);
		}

		queue<Data> q;
		Data q_front;
		bool memo[100][100] = {}, ans = false;
		q.push( Data(Ys, Xs) );
		while( !q.empty() ){
			q_front = q.front(); q.pop();

			if( fld[q_front.y][q_front.x] == 0 ||
				fld[q_front.y][q_front.x] != fld[Ys][Xs] )
				continue;

			if(q_front.y == Yg && q_front.x == Xg){
				ans = true; break;
			}

			if(memo[q_front.y][q_front.x]) continue;
			memo[q_front.y][q_front.x] = true;

			for(int i = 0; i < 4; i++){
				int ny = q_front.y + dy[i];
				int nx = q_front.x + dx[i];
				if(ny < 0 || H <= ny || nx < 0 || W <= nx) continue;
				q.push( Data(ny, nx) );
			}
		}
		
		if(ans) puts("OK");
		else puts("NG");
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
 
int C[102][102];
 
void meiro(int W,int H,int c){
  if(C[W][H]!=c){
    return;
  }
 
  C[W][H] = -1;
 
  meiro(W-1,H  ,c);
  meiro(W  ,H+1,c);
  meiro(W+1,H  ,c);
  meiro(W  ,H-1,c);
}
 
int main(){
  while(1){
    int w,h;
    cin >> w >> h;
    if(w==0 && h==0){
      break;
    }
 
    for(int i=0;i<102;i++){
      for(int j=0;j<102;j++){
        C[i][j] = 0;
      }
    }
 
    int xs,ys,xg,yg;
    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(d==0){
        for(int j=x;j<x+4;j++){
          for(int k=y;k<y+2;k++){
            C[j][k]=c;
          }
        }
      }else{
        for(int j=x;j<x+2;j++){
          for(int k=y;k<y+4;k++){
            C[j][k]=c;
          }
        }
      }
    }
 
    meiro(xs,ys,C[xs][ys]);
 
    if(C[xg][yg] == -1){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }
 
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

typedef long long lint;
typedef long double ldouble;
#define REP(i, x, n) for(int i = x ; i < n ; i++)
#define rep(i, n) REP(i, 0, n)
#define repr(i, n) for(int i = n - 1 ; i >= 0 ; i--)
#define SORT(c) sort((c).begin(), (c).end())

const int IINF = 1e9 + 10;
const lint LLINF = 1e18;
const lint MOD = 1e9 + 7;
const lint inv = MOD - 2;

vector< vector<int> > b;
int xs, ys, xg, yg;
int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};

bool dfs(int y, int x, int color){
    if(y == yg && x == xg){
        return true;
    }
    b[y][x] = -2;
    bool res = false;
    rep(i, 4){
        int ny = y + dy[i], nx = x + dx[i];
        if(b[ny][nx] == color){
            res = res || dfs(ny, nx, color);
        }
    }
    return res;
}

int main(){
    while(true){
        int w, h;
        cin >> w >> h;
        if(w == 0 && h == 0){
            break;
        }
        b.resize(h+2);
        rep(i, h+2){
            b[i].resize(w+2);
        }
        rep(i, h+2){
            rep(j, w+2){
                b[i][j] = -2;
            }
        }
        cin >> xs >> ys >> xg >> yg;
        int n;
        cin >> n;
        rep(k, n){
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            if(d == 0){
                REP(i, y, y+2){
                    REP(j, x, x+4){
                        b[i][j] = c;
                    }
                }
            }else{
                REP(i, y, y+4){
                    REP(j, x, x+2){
                        b[i][j] = c;
                    }
                }
            }
        }
        b[ys][xs] = max(b[ys][xs], -1);
        if(dfs(ys, xs, b[ys][xs])){
            cout << "OK" << endl;
        }else{
            cout << "NG" << endl;
        }
    }
    return 0;
}

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

int w, h, xs, ys, xg, yg, n;
int board[110][110];
bool used[110][110];

int dx1[8] = {0,1,2,3,0,1,2,3};
int dy1[8] = {0,0,0,0,1,1,1,1};

int dx2[8] = {0,0,0,0,1,1,1,1};
int dy2[8] = {0,1,2,3,0,1,2,3};

bool dfs(int x, int y, int xg, int yg, int color) {
    if (board[y][x] != color || used[y][x] || x <= 0 || y <= 0 || w < x || h < y) {
        return false;
    }
    if (x == xg && y == yg) {
        return true;
    }
    used[y][x] = true;
    bool ret = false;
    ret |= dfs(x+1, y, xg, yg, color);
    ret |= dfs(x-1, y, xg, yg, color);
    ret |= dfs(x, y+1, xg, yg, color);
    ret |= dfs(x, y-1, xg, yg, color);
    return ret;
}

int main() {
    while (cin >> w >> h, (w || h)) {
        memset(board, 0, sizeof board);
        cin >> xs >> ys >> xg >> yg >> n;
        int c, d, x, y;
        for (int i=0; i<n; ++i) {
            cin >> c >> d >> x >> y;
            if (d == 0) {
                for (int i=0; i<8; ++i) {
                    board[y + dy1[i]][x + dx1[i]] = c;
                }
            } else {
                for (int i=0; i<8; ++i) {
                    board[y + dy2[i]][x + dx2[i]] = c;
                }
            }
        }
        memset(used, false, sizeof used);
        if (dfs(xs, ys, xg, yg, c)) {
            cout << "OK" << endl;
        } else {
            cout << "NG" << endl;
        }
    }
    return 0;
}