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 <math.h>
#include <numeric>
#include <vector>
#include <map>
#include <functional>
#include <stdio.h>
#include <array>
#include <algorithm>
#include <string>
#include <assert.h>
#include <stdio.h>
#include <queue>
#include<iomanip>
#include<bitset>
#include<list>
using namespace std;

const int mod = 1000000007;

struct Mod {
	int num;
	Mod() : num(0) { ; }
	Mod(int n) : num((n % mod + mod) % mod) { ; }
	operator int() { return num; }
};

Mod operator+(Mod a, Mod b) { return Mod((a.num + b.num) % mod); }
Mod operator-(Mod a, Mod b) { return Mod((mod + a.num - b.num) % mod); }
Mod operator*(Mod a, Mod b) { return Mod(((long long)a.num * b.num) % mod); }
Mod operator+=(Mod &a, Mod b) { return a = a + b; }
Mod operator-=(Mod &a, Mod b) { return a = a - b; }
Mod operator*=(Mod &a, Mod b) { return a = a * b; }
Mod operator^(Mod a, int n) {
	if (n == 0) return Mod(1);
	Mod res = (a * a) ^ (n / 2);
	if (n % 2) res = res * a;
	return res;
}
Mod inv(Mod a) { return a ^ (mod - 2); }
Mod operator/(Mod a, Mod b) { 
assert(b!=0);
return a * inv(b);
 }

#define MAX_N 1024000

Mod fact[MAX_N], factinv[MAX_N];
void init() {
	fact[0] = Mod(1); factinv[0] = 1;
	for (int i = 0; i < MAX_N - 1; ++i) {
		fact[i + 1] = fact[i] * Mod(i + 1);
		factinv[i + 1] = factinv[i] / Mod(i + 1);
	}
}
Mod comb(int a, int b) {
	return fact[a] * factinv[b] * factinv[a - b];
}

#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()


int dx[4] = { -1,0,1,0 };
int dy[4] = { 0,-1,0,1 };
struct Node {
	Node(int a, int b, int c) {
		atime = a;
		x = b;
		y = c;
	}
	int atime;
	int x;
	int y;
};
class Compare {
public:
	bool operator()(const Node& l, const Node& r) {
		return l.atime < r.atime;
	}
};


int main() {
	while(1) {
		int w, h;
		cin >> w >> h;
		if (!w)return 0;
		vector<vector<int>> maze(w+h+2, vector<int>(w+h+2,0));

		int xs, ys, xg, yg;
		cin >> xs >> ys >> xg >> yg;
		int n;
		cin >> n;
		for (int i = 0; i < n; ++i) {
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			if (!d) {
				for (int ax = 0; ax < 4; ++ax) {
					for (int ay = 0; ay < 2; ++ay) {
						maze[y+ay][x+ax] = c;
					}
				}
			}
			else {
				for (int ax = 0; ax < 2; ++ax) {
					for (int ay = 0; ay < 4; ++ay) {
						maze[y + ay][x + ax] = c;
					}
				}
			}
		}
		/*for (int i = 0; i < maze.size(); ++i) {
			for (int j = 0; j < maze[0].size(); ++j) {
				cout << maze[i][j];
			}
			cout << endl;
		}*/
		int color = maze[ys][xs];
		if (!color||color!=maze[yg][xg]) {
			cout << "NG" << endl;
			continue;
		}
		
		vector<vector<bool>>times(h, vector<bool>(w, false));

		priority_queue<Node,vector<Node>,Compare> qu;
		 qu.emplace(0,xs,ys);
		 bool flag=false;
		while (!qu.empty()) {
			Node an(qu.top());
			qu.pop();
			if (an.x == xg&&an.y == yg) {
				flag = true;
				break;
			}
			else {
				for (int i = 0; i < 4; ++i) {
					if (maze[an.y + dy[i]][an.x + dx[i]] == color) {
						if (times[an.y + dy[i]][an.x + dx[i]]) {

						}
						else {
							qu.push(Node{ an.atime + 1,an.x + dx[i], an.y + dy[i] });
							times[an.y + dy[i]][an.x + dx[i]] = true;
						}
						
					}
				}
			}
		}
		if (flag) {
			cout << "OK" << endl;

		}
		else {
			cout << "NG" << endl;
		}
	}
	return 0;

}

C++: #include<iostream>
#include<cstdio>
using namespace std;
#define loop(i,a,b) for(int i = a ; i < b ; i++)
#define rep(i,a) for(int i = 0 ; i < a ; i ++)

int maze[104][104];
int h,w;
int sx,sy ,  gx,gy , n;
int co;
int dx[4] = {1,-1,0,0};
int dy[4] = {0,0,1,-1};

bool inmaze(int x,int y){
  return (0<=x && x<w) && (0<=y && y<h);
}

bool dfs(int x,int y){
  //cout<<"che"<<x<<" "<<y<<endl;
  if(x == gx && y == gy){
    return true;
    cout<<"ok"<<endl;
  }
  if(!inmaze(x,y))return false;
  maze[x][y] = 10;
  bool res = false;
  rep(i,4)
    if(maze[x + dx[i]][y + dy[i]] == co){
      res = dfs(x+dx[i],y+dy[i]);
      if(res)return true;
    }
  return res;
}

int main(void){
  while(cin>>w>>h,w+h){
    cin>>sx>>sy>>gx>>gy>>n;
    sx--,sy--,gx--,gy--;
    //cout<<sx<<" "<<sy<<" "<<gx<<" "<<gy<<endl;
    rep(i,h)rep(j,w)maze[i][j] = -1;
    rep(i,n){
      int c,b,x,y;
      cin>>c>>b>>x>>y;
      x--,y--;
      //cout<<x<<" "<<y<<endl;
      rep(i,(b?2:4))
	rep(j,(b?4:2))
	maze[i+x][j+y] = c;
    }
    co = maze[sx][sy];
    bool res = dfs(sx,sy); 
    cout<<(res?"OK":"NO")<<endl;
   
  }
}