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<bits/stdc++.h>
using namespace std;

int h,w;
int maps[100][100];
int color;
int gy,gx,sy,sx;
int dy[]={-1,0,1,0};
int dx[]={0,-1,0,1};
int muki[2][2]={
  {2,4},
  {4,2}
};
    
  

bool dfs(int y,int x);

int main(){
  int n;
  int c,d,y,x;
  while(cin >> w >> h,w | h){
    memset(maps,-1,sizeof(maps));
    cin >> sx >> sy >> gx >> gy;
    sx--;sy--;gx--;gy--;
    cin >> n;
    for(int i = 0; i < n; ++i){
      cin >> c >> d >> x >> y;
      for(int j = 0; j < muki[d][0]; j++){
	for(int k = 0;k < muki[d][1]; k++){
	  maps[y - 1 + j][x - 1 + k] = c;
	  if(y - 1 + j == sy && x - 1 + k == sx){
	    color = maps[sy][sx] = c;
	  }
	}
      }
    }

    /* for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	printf("%3d",maps[i][j]);
      }
      cout<<endl;
      }*/

    if(dfs(sy,sx))cout << "OK" << endl;
    else cout << "NO" << endl;
    
    /*
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	printf("%3d",maps[i][j]);
      }
      cout<<endl;
      }*/

  }
}

bool dfs(int y,int x){
  maps[y][x] = -1;
  if(gy==y && gx==x){
    return true;
  }
  bool b = false;
  for(int i=0;i<4;i++){
    int vy=y+dy[i];
    int vx=x+dx[i];
    if(vy >= 0 && vy < h && vx >= 0 && vx < w && maps[vy][vx] != -1 && maps[vy][vx] == color){
      b = b | dfs(vy,vx);
    }
  }
  return b;
}

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

struct block{
  int x, y, c;
  bool var;//0テ」ツ?ョテヲツ卍?*4, 1テ」ツ?ョテヲツ卍?*2
  block(int c_, bool var_, int x_, int y_):
    c(c_), var(var_), x(x_), y(y_){
  };
  int GetWidth(){
    if(var)return 2;
    else return 4;
  }
  int GetHight(){
    if(var)return 4;
    else return 2;
  }
};

void paint(vector<string>& grid, block b){
  for (int i = b.y; i < b.y + b.GetHight(); i++) {
    for (int j = b.x; j < b.x + b.GetWidth(); j++) {
      grid[i][j] = b.c + '0';
    }
  }
}
int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
int w, h;

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

bool dfs(vector<string>& grid, vector<vector<bool> > &visited,
         int x, int y, int gx, int gy, char c){
  if(x == gx && y == gy)return true;
  bool res = false;
  for (int i = 0; i < 4; i++) {
    if(!range(x + dx[i], y + dy[i]))continue;
    if(visited[y + dy[i]][x + dx[i]] == true)continue;
    if(grid[y + dy[i]][x + dx[i]] != c)continue;
    visited[y + dy[i]][x + dx[i]] = true;
    res |= dfs(grid, visited, x + dx[i], y + dy[i], gx, gy, c);
  }
  return res;
}

int main(int argc, char *argv[]){
  while(std::cin >> w >> h, w){
    int sx, sy, gx, gy, n;
    std::cin >> sx >> sy >> gx >> gy >> n;
    sx--;sy--;gx--;gy--;
    vector<string> grid(h, string(w, '.'));
    vector<block> b;
    for (int i = 0; i < n; i++) {
      int c, d, x, y;
      std::cin >> c >> d >> x >> y;
      x--;y--;
      b.push_back(block(c, d, x, y));
      paint(grid, b[i]);
    }
    // for (int i = 0; i < grid.size(); i++) {
    //   std::cout << grid[i] << std::endl;
    // }
    vector<vector<bool> > visited(h, vector<bool>(w, false));
    visited[sy][sx] = true;;
    if(dfs(grid, visited, sx, sy, gx, gy, grid[sy][sx])){
      std::cout << "OK" << std::endl;
    }else{
      std::cout << "NG"<< std::endl;
    }

  }
  return 0;
}

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

int w, h;
vector < vector <int> > block_map;
vector < vector <bool> > visited;

int xs, ys;
int xg, yg;

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

bool dfs( int x, int y )
{
	if ( block_map[x][y] != block_map[xg][yg] )
		return false;
	if ( x == xg && y == yg )
		return true;

	for ( int i = 0; i < 4; i++ )
	{
		int nx = x + dx[i];
		int ny = y + dy[i];
		if ( nx < 0 || nx >= w || ny < 0 || ny >= h )
			continue;

		if ( visited[ny][nx] == false && block_map[ny][nx] == block_map[ys][xs] )
		{
			visited[ny][nx] = true;
			if ( dfs( nx, ny ) )
			{
				return true;
			}
			visited[ny][nx] = false;
		}
	}

	return false;
}

int main( void )
{
	while ( 1 )
	{
		cin >> w >> h;
		if ( w == 0 && h == 0 )
			break;

		block_map = vector < vector <int> >( h, vector <int>(w,0) );
		visited = vector < vector <bool> >( h, vector <bool>(w,false) );

		cin >> xs >> ys >> xg >> yg;

		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;
			x--;
			y--;

			if ( d == 0 )
			{
				for ( int by = 0; by < 2; by++ )
				{
					for ( int bx = 0; bx < 4; bx++ )
					{
						block_map[y+by][x+bx] = c;
					}
				}
			}
			else
			{
				for ( int by = 0; by < 4; by++ )
				{
					for ( int bx = 0; bx < 2; bx++ )
					{
						block_map[y+by][x+bx] = c;
					}
				}
			}
		}

		if ( dfs( xs, ys ) )
			cout << "OK" << endl;
		else
			cout << "NG" << endl;

	}
	return 0;
}