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<algorithm>
#include<vector>
#include<string>
#define ll long long
#define loop(i,n) for (int i = 0; i < n; i++)
#define loops(i,f,n) for (int i = (f); i < n; i++)
#define INF 100000000000000
#define sort(a) sort(a.begin(),a.end())
#define rsort(a) sort(a.rbegin(),a.rend())
using namespace std;
int w, h, sx, sy, gx, gy, n;
vector <vector<int > > grid(105, vector<int>(105));
vector <vector<bool > > grid_visited(105, vector<bool>(105, false));
void input(int c, int d, int x, int y)
{
    if (d == 0)//yokonaga
    {
        loop(i, 2)
        {
            loop(j, 4)
            {
                grid[y + i][x + j] = c;
            }
        }
    }
    else//tatenaga
    {
        loop(i, 4)
        {
            loop(j, 2)
            {
                grid[y + i][x + j] = c;
            }
        }
    }
}
    bool a=false;
bool dfs(int nx, int ny)
{
    if (nx == gx&&ny == gy)return true;
    if (nx < 0 || ny < 0 || nx >= h || ny >= w || grid[nx][ny] == 0 || grid_visited[nx][ny])return false;
    grid_visited[nx][ny] = true;
    if((nx+1) >= 0 && ny >= 0 && (nx+1) < h && ny < w)if(grid[nx + 1][ny]== grid[nx][ny])a|=dfs(nx + 1, ny);
    if(nx >= 0 && (ny+1) >= 0 && nx < h && (ny+1) < w)if(grid[nx][ny+1]== grid[nx][ny])a|=dfs(nx, ny+1);
    if((nx-1) >= 0 && ny >= 0 && (nx-1) < h && ny < w)if(grid[nx - 1][ny]== grid[nx][ny])a|=dfs(nx - 1, ny);
    if(nx >= 0 && (ny-1) >= 0 && nx < h && (ny-1) < w)if(grid[nx][ny-1]== grid[nx][ny])a|=dfs(nx, ny-1);
    //return (dfs(nx + 1, ny) || dfs(nx, ny + 1) || dfs(nx - 1, ny) || dfs(nx, ny - 1));
    return a;
    return false;
}
int main()
{
    while (1)
    {
        cin >> w >> h;
        if (!w && !h) break;
        else
        {
            cin >> sx >> sy >> gx >> gy >> n;
            sx--; sy--; gx--; gy--;
            loop(i, n)
            {
                int c, d, x, y;
                cin >> c >> d >> x >> y;
                x--; y--;
                input(c, d, x, y);
            }
            /*loop(i, h)
            {
                loop(j, w)
                {
                    cout << grid[i][j] << " ";
                }
                cout << endl;
            }*/
            a=false;
            
            cout << (dfs(sx, sy) ? "OK" : "NG") << endl;
        }
    }
 
}

C++: #include<iostream>
#include<queue>
#include<vector>
#include<list>

typedef struct block
{
	int x;
	int y;
	int h;
	int w;
	int color;
}block;

block blocks[1280];

std::queue<int> que;
std::list<int> adjacive[1280];

void makelist(int n);
bool BFS(int start,int goal);

int main()
{
	int n,w,h,xs,ys,xg,yg,start,goal;
	while(1)
	{
		while(!que.empty()){que.pop();}
		start=0;
		goal=0;
		std::cin>>w>>h;
		if(w==0&&h==0)break;
		std::cin>>xs>>ys>>xg>>yg>>n;
		for(int i=0;i<n;i++)
		{
			int c,d,x,y;
			std::cin>>c>>d>>x>>y;
			blocks[i].color=c;
			blocks[i].x=x;
			blocks[i].y=y;
			if(d==0)
			{
				blocks[i].h=2;
				blocks[i].w=4;
			}
			else
			{
				blocks[i].h=4;
				blocks[i].w=2;
			}
			if(blocks[i].x<=xs&&blocks[i].x+blocks[i].w>=xs&&blocks[i].y<=ys&&blocks[i].y+blocks[i].h>=ys)
			{
				start=i;
			}
			else if(blocks[i].x<=xg&&blocks[i].x+blocks[i].w>=xg&&blocks[i].y<=yg&&blocks[i].y+blocks[i].h>=yg)
			{
				goal=i;
			}
		}
		makelist(n);
		if(BFS(start,goal))
		{
			std::cout<<"OK"<<std::endl;
		}
		else
		{
			std::cout<<"NG"<<std::endl;
		}
	}
	return 0;
}

void makelist(int n)
{
#define x1 blocks[i].x
#define y1 blocks[i].y
#define h1 blocks[i].h
#define w1 blocks[i].w
#define x2 blocks[j].x
#define y2 blocks[j].y
#define h2 blocks[j].h
#define w2 blocks[j].w

	for(int i=0;i<n;i++)
	{
		adjacive[i].clear();
		for(int j=0;j<n;j++)
		{
			if(blocks[i].color==blocks[j].color)
			{
				if((x1==x2+w2&&y1<=y2+h2&&y1+h1>=y2)||(x2==x1+w1&&y1<=y2+h2&&y1+h1>=y2)||(y1==y2+h2&&x1<=x2+w2&&x1+w1>=x2)||(y2==y1+h1&&x1<=x2+w2&&x2<=x1+w1))
				{
					adjacive[i].push_back(j);
				}
			}
		}
	}
}

bool BFS(int start,int goal)
{
	int survey;
	que.push(start);
	
	while(!que.empty())
	{
		survey=que.front();
		que.pop();
		for(std::list<int>::iterator it=adjacive[survey].begin();it!=adjacive[survey].end();it++)
		{
				que.push(*it);
		}
		adjacive[survey].clear();
		if(survey==goal)
		{
			return true;
		}
	}
	return false;
}

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


#define rep(i,n) for(int i = 0; i < n; i++)
#define MAX 50

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

typedef pair<int,int> P;
P S,G;
int w,h;
int maze[MAX][MAX];
int color;

bool check()
{
	queue<P> que;
	que.push(S);
	color = maze[S.second][S.first];

	int nx,ny;
	while(que.size()){
		P p = que.front();	que.pop();

		if(p == G){
			while(que.size())
				que.pop();
			return true;
		}

		rep(i,4){
			nx = p.first + dx[i], ny = p.second + dy[i];
			
			if(nx > -1 && ny > -1 && nx < w && ny < h &&
				maze[ny][nx] == color){
					maze[ny][nx] = -1;
					que.push(P(nx,ny));
			}

		}
	}


	
	return false;
}

int main(void)
{
	int n,c,d,x,y;

	while(cin >> w >> h, w){
		cin >> S.first >> S.second;
		cin >> G.first >> G.second;
		S.first = S.first / 2;
		S.second= S.second/ 2;

		cin >> n;

		rep(i,n){
			cin >> c >> d >> x >> y;
			x /= 2;
			y /= 2;
			x++;
			y++;

			if(d == 0)
				maze[y][x] = maze[y][x+1] = c;
			else
				maze[y][x] = maze[y+1][x] = c;
		}
		
		if(check())
			cout << "OK\n";
		else
			cout << "NG\n";
/*
		rep(i,y){
			rep(j,x)
				printf("%2d", maze[i][j]);
			cout << endl;
		}

*/
	}
	
	return 0;
}