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>
#include<vector>
#include<queue>
using namespace std;

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


class cordinate
{

public:
	int x;
	int y;

};

int main()
{
	while(1)
	{


		int w;
		int h;
		cin >> w >> h; 
		if(w == 0 && h == 0)
		{
			break;
		}
		int xs;
		int ys;
		cin >> xs >> ys;
		int xg;
		int yg;
		cin >> xg >> yg;
		int n;
		cin >> n;

		vector<vector<int >> vobj;

		for(int i = 0; i < h; i++)
		{
			vector<int> lineobj;
			for(int j = 0; j < w; j++)
			{

				lineobj.push_back(0);

			}
			vobj.push_back(lineobj);

		}
		for(int i = 0; i < n; i++)
		{
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			x--;
			y--;

			if(d == 0)
			{
				vobj[x][y] = c;
				vobj[x + 1][y] = c;
				vobj[x + 2][y] = c;
				vobj[x + 3][y] = c;
				vobj[x][y + 1] = c;
				vobj[x + 1][y + 1] = c;
				vobj[x + 2][y + 1] = c;
				vobj[x + 3][y + 1] = c;
			}
			else if(d == 1)
			{
				vobj[x][y] = c;
				vobj[x][y + 1] = c;
				vobj[x][y + 2] = c;
				vobj[x][y + 3] = c;
				vobj[x + 1][y] = c;
				vobj[x + 1][y + 1] = c;
				vobj[x + 1][y + 2] = c;
				vobj[x + 1][y + 3] = c;
			}
		}

		int startColor;
		startColor = vobj[xs - 1][ys - 1];
		queue<cordinate> que;

		cordinate obj;
		obj.x = xs - 1;
		obj.y = ys - 1;
		que.push(obj);
		bool flag = false;
		while(1)
		{
			if(startColor == 0)
			{
				break;
			}
			cordinate buf;
			buf = que.front();
			que.pop();

			int bx;
			int by;
			bx = buf.x;
			by = buf.y;
			if(bx == xg - 1 && by == yg - 1)
			{
				flag = true;
				break;
			}
			for(int i = 0; i < 4; i++)
			{
				if(bx + dx[i] >= 0 && bx + dx[i] <= h - 1)
				{
					if(by + dy[i] >= 0 && by + dy[i] <= w - 1)
					{
						if(vobj[bx + dx[i]][by + dy[i]] == startColor)
						{
							cordinate newObject;
							newObject.x = bx + dx[i];
							newObject.y = by + dy[i];
							que.push(newObject);

						}
					}
				}
			}
			vobj[bx][by] = -1;

			if(que.size() == 0)
			{
				break;
			}
		}


		if(flag == true)
		{
			cout << "OK" << endl;
		}
		else{
			cout << "NG" << endl;
		}
		/*for(int i = 0; i < w - 1; i++)
		{
			for(int j = 0; j < h - 1; j++)
			{
				cout << vobj[i][j] << " ";
			}
			cout << endl;
		}  */

	}



}

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 == gy && y == gx){
    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;
   
  }
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<time.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double EPS=1e-10;
const int inf=1e8;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
int sx,sy;
int gx,gy;
vvi tmp;
int dx[]={0,0,1,-1};
int dy[]={-1,1,0,0};
void solve(int x,int y){
	tmp[x][y]=-1;
	rep(i,4){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(tmp[nx][ny]==2)solve(nx,ny);
	}
}
int main(){
	int n,m;
	while(cin>>n>>m,n+m){
		vvi in(n+2,vi(m+2));
		cin>>sx>>sy>>gx>>gy;
		cin>>n;
		while(n--){
			int a,b,c,d;
			cin>>a>>b>>c>>d;
			if(!b)rep(i,4)rep(j,2)in[c+i][d+j]=a;
			else rep(i,2)rep(j,4)in[c+i][d+j]=a;
		}
		tmp=in;
		if(in[sx][sy]==2)solve(sx,sy);
		//rep(i,22){rep(j,22)cout<<in[i][j]<<" ";cout<<endl;}
		cout<<((in[sx][sy]==2&&in[gx][gy]==2&&tmp[gx][gy]==-1)?"OK":"NG")<<endl;
		//rep(i,22){rep(j,22)cout<<tmp[i][j]<<" ";cout<<endl;}
	}
}