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 <cctype>
#include <limits.h>
#include <math.h>
#include <complex>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <cstring>
#include <string>
#include <sstream>
#include <algorithm>
#include <iomanip>
#include <iostream>

#define VARIABLE(x) cerr << #x << "=" << x << endl
#define BINARY(x) static_cast<bitset<16> >(x);
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,m,n) for (int i=m;i<(int)(n);i++)
#define if_range(x, y, w, h) if (0<=(int)(x) && (int)(x)<(int)(w) && 0<=(int)(y) && (int)(y)<(int)(h))

const int INF = 1e9;
const double EPS = 1e-8;
const double PI = 3.14159;
int dx[4]={0, 1, 0, -1}, dy[4]={-1, 0, 1, 0};
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
/* struct P {
	int x, y, n;
	P(int n, int x, int y):n(n), x(x), y(y){}
	P(){}
}; */

/** Problem0207 : Block **/
int main()
{
	int W, H;
	
	while (cin>>W>>H, W||H) {
		vector<vector<int> > board(W, vector<int>(H));
		int sx, sy, gx, gy;
		cin>>sx>>sy>>gx>>gy;
		sx--, sy--, gx--, gy--;
		
		int N; cin>>N;
		while (N--) {
			int c, d, x, y; cin>>c>>d>>x>>y;
			x--, y--;
			
			if (d==0) {
				board[x][y] = board[x+1][y] = board[x+2][y] = board[x+3][y] = c;
				board[x][y+1] = board[x+1][y+1] = board[x+2][y+1] = board[x+3][y+1] = c;
			} else {
				board[x][y] = board[x][y+1] = board[x][y+2] = board[x][y+3] = c;
				board[x+1][y] = board[x+1][y+1] = board[x+1][y+2] = board[x+1][y+3] = c;
			}
		}
		
		/**
		rep(i, H) {
			rep(j, W) {
				cerr << board[j][i] << " ";
			}
			cerr << endl;
		} **/
		
		queue<P> Q;
		bool vis[100][100]={0};
		Q.push(P(sx, sy));
		vis[sx][sy]=true;
		
		while (Q.size()) {
			P p = Q.front(); Q.pop();
			if (p.first == gx && p.second == gy) {
				cout << "OK" << endl;
				goto end;
			}
			rep(i, 4) {
				int nx = p.first+dx[i], ny = p.second+dy[i];
				if_range(nx, ny, W, H) {
					if (!vis[nx][ny] && board[nx][ny] == board[p.first][p.second]) {
						Q.push(P(nx, ny));
						vis[nx][ny] = true;
					}
				}
			}
		}
		cout << "NG" << endl;
	end:;
	}
}

C++: #include <iostream>
using namespace std;
 
int F[105][105];
int xg,yg;
 
 
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
 
  F[Y][X] = -2;
  DFS(Y-1,X  ,c);
  DFS(Y  ,X+1,c);
  DFS(Y+1,X  ,c);
  DFS(Y  ,X-1,c);
}
 
 
int main(){
  int w,h,xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<20; i++){
      for(int j=0; j<20; j++){
        F[i][j]=2;
      }
    }
     
    cin >> xs >> ys >> xg >> yg >> n;
 
 
    for(int i=0;i<n;i++){
      int c,d,x,y;
      cin >> c >> d >> x >> y;
      if(d == 0){
        for(int j=0;j<4;j++){
          F[x+j][y] = c;
          F[x+j][y+1] = c;
        }
      } else {
        for(int j=0;j<4;j++){
          F[x][y+j] = c;
          F[x+1][y+j] = c;
        }
      }
    }

  DFS(xs,ys,F[xs][ys]);
 
  if(F[xg][yg] == -2){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

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

int F[102][102] = { 0 };

void DFS(int Y, int X, int c) {
	//cout << Y << " " << X << endl;
	if (F[Y][X] != c)
		return;
	F[Y][X] = 10;
	DFS(Y - 1, X, c);//???
					 //DFS(Y - 1, X+1, A_ito);//??????
	DFS(Y, X + 1, c);//???
					 //DFS(Y + 1, X+1, A_ito);//??????
	DFS(Y + 1, X, c);//???
					 //DFS(Y + 1, X-1, A_ito);//??????
	DFS(Y, X - 1, c);//???
					 //DFS(Y - 1, X-1, A_ito);//??????
}


int main()
{
	int xs, ys, xg, yg, n;
	int c, d, x, y;
	int W = 1, H = 1;

	while ((W != 0) && (H != 0)) {
		cin >> W >> H;
		for (int i = 1;i <= H;i++) {
			for (int j = 1;j <= W;j++) {
				F[i][j] = 6;
			}
		}
		cin >> xs >> ys >> xg >> yg >> n;
		for (int i = 1;i <= n;i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				F[x][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y] = c;
				F[x + 1][y + 1] = c;
				F[x + 2][y] = c;
				F[x + 2][y + 1] = c;
				F[x + 3][y] = c;
				F[x + 3][y + 1] = c;
			}
			if (d == 1) {
				F[x][y] = c;
				F[x + 1][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y + 1] = c;
				F[x][y + 2] = c;
				F[x + 1][y + 2] = c;
				F[x][y + 3] = c;
				F[x + 1][y + 3] = c;
			}
		}
		if(F[ys][xs]!=0)
			DFS(ys, xs, F[ys][xs]);

		if (F[yg][xg] == F[ys][yg]) {
			cout << "OK" << endl;
		}
		else { cout << "NG" << endl; }
		for (int i = 0;i <= H;i++) {
			for (int j = 0;j <= W;j++) {
				F[i][j] = 0;
			}
		}
		
	}

	return 0;
}