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>
#pragma region defins
#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;
#pragma endregion
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 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;
    bool a=false;
    if(grid[nx + 1][ny]== grid[nx][ny])a|=dfs(nx + 1, ny);
    if(grid[nx][ny+1]== grid[nx][ny])a|=dfs(nx, ny+2);
    if(grid[nx - 1][ny]== grid[nx][ny])a|=dfs(nx - 1, ny);
    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;
            }*/
            cout << (dfs(sx, sy) ? "OK" : "NG") << endl;
        }
    }
 
}

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

int F[102][102];
int xg,yg;

int DFS(int Y,int X,int c){
  if(F[Y][X]!=c){
    return 0;
  }
  if(Y == xg && X == yg){
    return 1;
  }

  F[Y][X] = 0;
  return(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;
  cin >> w >> h >> 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;
      }
    }
  }


  if(DFS(xs,ys,F[xs][ys]) == 1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }

}

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

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

int main()
{
	int w, h;
	while( cin >> w >> h && ( w || h ) ){
		int* map = new int[ ( w + 2 ) * ( h + 2 ) ]();
		int xs, ys, xg, yg;
		cin >> xs >> ys;
		cin >> xg >> yg;
		int n;
		cin >> n;
		for( int i = 0; i < n; ++i ){
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			for( int j = 0; j < 2; ++j ){
				if( d == 0 ) x += ( 2 * j );
				else y += ( 2 * j );
				for( int k = y; k < y + 2; ++k ){
					for( int m = x; m < x + 2; ++m ){
						map[ k * ( w + 2 ) + m ] = c;
					}
				}
			}
		}
		bool ans = false;
		int cs, cg;
		cs = map[ ys * ( w + 2 ) + xs ];
		cg = map[ yg * ( w + 2 ) + xg ];
		if( !( cs == 0 || cg == 0 || cs != cg ) ){
			queue< pair< int, int > > q;
			q.push( make_pair( xs, ys ) );
			while( !q.empty() ){
				int x = q.front().first;
				int y = q.front().second;
				q.pop();
				if( x == xg && y == yg ){
					ans = true;
					break;
				}
				map[ y * ( w + 2 ) + x ] = 0;
				for( int i = 0; i < 4; ++i ){
					int nx = x + dx[ i ];
					int ny = y + dy[ i ];
					if( map[ ny * ( w + 2 ) + nx ] == cs ){
						q.push( make_pair( nx, ny ) );
					}
				}
			}
		}
		cout << ( ans ? "OK" : "NG" ) << endl;
		delete[] map;
	}
	return 0;
}

C++: #define _USE_MATH_DEFINES
#define INF 10000000
#include <iostream>
#include <sstream>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>

using namespace std;

typedef long long ll;
typedef pair<int,int> P;

static const double eps = 1e-8;

int moveTo[][2] = {{-1,0},{1,0},{0,-1},{0,1}};

int stage[100][100];

void paint(int c,int d,int x,int y){
	//c:1~5 d: 0:horizonal 1:vertical
	if(d==0){
		for(int i=x;i<x+4;i++){
			for(int j=y;j<y+2;j++){
				stage[j][i] = c;
			}
		}
	}
	else{
		for(int i=x;i<x+2;i++){
			for(int j=y;j<y+4;j++){
				stage[j][i] = c;
			}
		}
	}
}

bool bfs(int w, int h, int xs, int ys, int xg, int yg){
	int cs = stage[ys][xs];
	int cg = stage[yg][xg];
	if(cs != cg) return false;

	queue<P> que;
	que.push(P(ys,xs));

	while(!que.empty()){
		int sx = que.front().first;
		int sy = que.front().second;
		
		if(sx == xg && sy == yg) return true;
		que.pop();

		stage[sy][sx] = -1;

		for(int i=0;i<4;i++){
			int dx = sx + moveTo[i][0];
			int dy = sy + moveTo[i][1];

			if(dx < 0 || dx >= w || dy < 0 || dy >= h) continue;
			if(stage[dy][dx] != cs || stage[dy][dx] == -1) continue;
			que.push(P(dx,dy));

		}

	}
	return false;
}

int main(){
	int w,h;
	while(~scanf("%d %d",&w,&h)){
		if(w==h && h==0) break;
		int xs,ys;
		scanf("%d %d",&xs,&ys);

		int xg,yg;
		scanf("%d %d",&xg,&yg);

		int n;
		scanf("%d",&n);
		for(int i=0;i<n;i++){
			int c,d,x,y;
			//c:1~5 d: 0:horizonal 1:vertical
			scanf("%d %d %d %d",&c,&d,&x,&y);
			paint(c,d,x,y);
		}

		printf("%s\n",bfs(w,h,xs,ys,xg,yg) ? "OK" : "NG");
	}
}