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>
using namespace std;

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

int w,h,xs,ys,xg,yg,n,cc;
int field[100][100];
bool flag;

void dfs(int x,int y,int c){
	if(flag) return;
	if(x == xg && y == yg) {
		flag = true;
		return;
	}
	for(int i = 0;i < 4;i++){
		int nx = x + dx[i],ny = y + dy[i];
		if(nx >= 0 && nx < w && ny >= 0 && ny < h && field[nx][ny] == c){
			field[nx][ny] = 0;
			dfs(nx,ny,c);
			field[nx][ny] = c;
		}
	}
}

int main(){
	while(1){
		flag = false;
		cin >> w >> h;
		if(!w) break;
		for(int i = 0;i < w;i++){
			for(int j = 0;j < h;j++) field[i][j] = 0;
		}
		cin >> xs >> ys >> xg >> yg >> n; xs--;ys--;xg--;yg--;
		for(int i = 0;i < n;i++){
			int c,d,x,y;
			cin >> c >> d >> x >> y;
			if(d == 1){
				for(int k = 0;k < 2;k++){
					for(int j = 0;j < 4;j++) field[x + k - 1][y + j - 1] = c;
				}
			}else{
				for(int k = 0;k < 4;k++){
					for(int j = 0;j < 2;j++) field[x + k - 1][y + j - 1] = c;
				}
			}
		}
		if(field[xs][ys] == 0){
			cout << "NG" << endl;
			continue;
		}
		cc = field[xs][ys];
		field[xs][ys] = 0;
		dfs(xs,ys,cc);
		if(flag) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
	return 0;
}

C++: /* 0207 */
#include <iostream>
using namespace std;
int n,w,h;
int M[101][101];
int a,b,c,d;

int walk(int x,int y,int color){
	if(x<1||w<x||y<1||h<y)return 0;
	if(color!=M[x][y]||color==0)return 0;
	M[x][y]=9;
	if(x==c&&y==d)return 1;
	if(walk(x+1,y,color)||
			walk(x-1,y,color)||
			walk(x,y+1,color)||
			walk(x,y-1,color))return 1;
	return 0;
}
int main(void){
	while(cin>>w>>h,w||h){
		cin>>a>>b>>c>>d;
		for(int i=1;i<=h;i++){
			for(int j=1;j<=w;j++){
				M[i][j]=0;
			}
		}
		int k;
		cin>>k;
		for(int i=0;i<k;i++){
			int w,x,y,z;
			cin>>w>>x>>y>>z;
			if(x){
				for(int Y=z;Y<z+4;Y++){
					for(int X=y;X<y+2;X++){
						M[Y][X]=w;
					}
				}
			}else{
				for(int Y=z;Y<z+2;Y++){
					for(int X=y;X<y+4;X++){
						M[Y][X]=w;
					}
				}
			}
		}
		// for(int i=1;i<=h;i++){
		// 	for(int j=1;j<=w;j++){
		// 		cout<<M[i][j]<<" ";
		// 	}
		// 	cout<<endl;
		// }
		if(a==c&&b==d||walk(a,b,M[a][b]))cout<<"OK"<<endl;
		else cout<<"NG"<<endl;
		// if(M[c][d]==9)cout<<"OK"<<endl;
		// else cout<<"NG"<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<cstring>

using namespace std;

int w,h;
int map[105][105];
int xg,yg;

int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
void mapout()
{
  cout<<endl;
  for(int xx=0;xx<h;xx++,cout<<endl)
    for(int yy=0;yy<w;yy++)
      if(map[xx][yy]!=-1)
      cout<<map[xx][yy];
      else
	cout<<"X";
  cout<<endl;
}

bool check(int x,int y)
{
  //  cout<<"check "<<x<<" "<<y<<";"<<map[x][y]<<endl;
  if(x==xg&&y==yg)
    return true;
  int buf=map[x][y];
  map[x][y]=-1;
  for(int i=0;i<4;i++)
    {
      if(x+dx[i]>0&&x+dx[i]<=h&&
	 y+dy[i]>0&&y+dy[i]<=w&&
	 buf==map[x+dx[i]][y+dy[i]] &&
	 map[x+dx[i]][y+dy[i]]!=-1 &&
	 check(x+dx[i],y+dy[i]))
	return true;
    }

  
  return false;
}

int main()
{
  for(;cin>>w>>h,w;)
    {
      memset(map,-1,sizeof(map));
      int xs,ys;
      cin>>xs>>ys;
      cin>>xg>>yg;
      //      xs--;ys--;
      //      xg--;yg--;
      
      int n;
      cin>>n;
      for(;n--;)
	{
	  int c,d,x,y;
	  cin>>c>>d>>y>>x;
	  ///  x--;y--;
	  if(d==0)
	    {
	      for(int xx=x;xx<x+2;xx++)
		for(int yy=y;yy<y+4;yy++)
		  map[xx][yy]=c;
	    }
	  else
	    {
	      for(int xx=x;xx<x+4;xx++)
		for(int yy=y;yy<y+2;yy++)
		  map[xx][yy]=c;
	    }
	}
      //   mapout();
      //	 cout<<xs<<" "<<ys<<" "<<map[xs][ys]<<endl;
      if(check(xs,ys))
	cout<<"OK"<<endl;
      else 
	cout<<"NG"<<endl;
      // mapout();
    }  
}

C++: #include <iostream>
#include <stack>
#include <complex>

using namespace std;

typedef complex<int> P;

int main() {
	int W, H;
	while (cin >> W >> H, W || H) {
		int sx, sy; cin >> sx >> sy; --sx, --sy;
		int gx, gy; cin >> gx >> gy; --gx, --gy;
		int n; cin >> n;

		int board[100][100] = {0};
		for (int i = 0; i < n; ++i) {
			int c, d, x, y; cin >> c >> d >> x >> y; --x, --y;
			int lx = x, ly = y;
			int rx, ry;

			if (d == 0) rx = x + 4, ry = y + 2;
			else rx = x + 2, ry = y + 4;

			for (y = ly; y < ry; ++y)
				for (x = lx; x < rx; ++x)
					board[y][x] = c;
		}

		bool f = false;
		P goal = P(gx, gy);
		int color = board[sy][sx];

		if (color == 0) {
			cout << "NG" << endl;
			continue;
		}

		stack<P> S; S.push( P(sx, sy) );
		while ( !S.empty() ) {
			P p = S.top(); S.pop();

			if (p.real() < 0 || p.real() >= W || p.imag() < 0 || p.imag() >= H) continue;
			if (board[p.imag()][p.real()] != color) continue;
			board[p.imag()][p.real()] = 0;

			if ( p == goal ) {
				cout << "OK" << endl;
				f = true;
				break;
			}

			S.push( p + P(1, 0) );
			S.push( p + P(-1, 0) );
			S.push( p + P(0, 1) );
			S.push( p + P(0, -1) );
		}
		if (f) continue;

		cout << "NG" << endl;
	}
}