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<stdio.h>
int w,h;
int is(int x,int y){
	return (x>=0 && x < w && y>=0 && y< h);
}
int main(void){
	const int dx[4]={0,1,0,-1};
	const int dy[4]={1,0,-1,0};
	int qx[100000];
	int qy[100000];
	int p,mx;
    int n,m[101][101]={0};
    int xs,ys,xg,yg,a,c,d,x,y,cnt,f;
	for(;;){
		scanf("%d %d",&w,&h);
		//printf("%d %d\n",w,h);
		if(w==0)break;
		for(int i=0;i<w;i++){
			for(int j=0;j<h;j++){
				m[i][j]=0;
			}
		}
		scanf("%d %d %d %d",&xs,&ys,&xg,&yg);
		scanf("%d",&n);
		for(int i=0;i<n;i++){
			scanf("%d %d %d %d",&c,&d,&x,&y);
			for(int j=0;j<(d==0?2:4);j++){
				for(int k=0;k<(d==0?4:2);k++){
					m[x-1+k][y-1+j]=c;
				}
			}
		}
		c = m[xs-1][ys-1];
		p=0;
		mx=1;
		qx[0]=xs-1;
		qy[0]=ys-1;
		f=1;
/*
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				printf("%d ",m[j][i]);
			}
			puts("");
		}
				printf("%d\n",c);*/
		while(f && p<mx){
			cnt = 0;
			for(int i=0;i<4;i++){
				x = qx[p] + dx[i];
				y = qy[p] + dy[i];
				if(is(x,y) && m[x][y] == c){
					m[x][y]=-1;
					cnt++;
					qx[p+cnt] = x;
					qy[p+cnt] = y;
					if(x == xg-1 && y == yg-1)f=0;
				}
			}
			mx += cnt;
			p++;
		}
		puts(f?"NG":"OK");
	}
    return 0;
}

C++: #include <iostream>
using namespace std;
 
int F[105][105];
int xg,yg;
 
 
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
 
  F[Y][X] = -1;
  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;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<102; i++){
      for(int j=0; j<102; j++){
        F[i][j]=0;
      }
    }
     
    cin >> 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;
        }
      }
    }

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

C++: #include <cstdio>
#include <cstring>
#include <vector>
#include <map>
#include <algorithm>

#define rep(i, j) FOR(i, 0, j)
#define FOR(i, j, k) for(int i = j; i < k; ++i)

using namespace std;

int w, h, xs, ys, xg, yg, n, c, d, x, y, b[101][101];
int dx[] = {0, -1, 0, 1}, dy[] = {-1, 0, 1, 0};

bool dfs(int x, int y){
  int nx, ny;
  b[x][y] = 0;
  if(x == xg && y == yg) return true;
  bool r = 0;
  rep(i, 4){
    nx = x + dx[i]; ny = y + dy[i];
    if(nx > 0 && nx <= h && ny > 0 && ny <= w && b[nx][ny]==c)r=r||dfs(nx, ny);
  }
  return r;
}

int main(){
  while(scanf("%d %d", &w, &h) && w && h){
    memset(b, 0, sizeof(b));
    scanf("%d%d%d%d", &ys, &xs, &yg, &xg);
    scanf("%d", &n);
    rep(i, n){
      scanf("%d%d%d%d", &c, &d, &y, &x);
      rep(j, (d?4:2)) rep(k, (d?2:4)) b[x + j][y + k] = c;
    }

    c = b[xs][ys];
    if(dfs(xs, ys)) puts("OK");
    else puts("NG");
  }
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define ANSWER(x) cout<<x<<endl
#define debug(x) cout<<#x<<": "<<x
const int BA = 1000;
const int INFTY = (1<<21);
int xg,yg,w,h,gc;
int maps[101][101];
int solve(int xs,int ys);
int main(){
  int tate[2] = {2,4};
  int yoko[2] = {4,2};
  int xs,ys,n;
  int c[101],d[101],x[101],y[101];
  while(1){
    fill(maps[0],maps[101],0);
    cin >> w >> h;
    if(w==0 && h==0)break;
    cin >> xs >> ys >> xg >> yg >> n;
    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];
    }
    for(int i=0;i<n;i++){
      for(int j=y[i];j<y[i]+tate[d[i]];j++){
	for(int k=x[i];k<x[i]+yoko[d[i]];k++){
	  if(j == ys && k == xs)gc = c[i];
	  maps[j-1][k-1] = c[i];
	}
      }
    }
    /* for(int i=0;i<h;i++){
       for(int j=0;j<w;j++){
       cout << maps[i][j];
       }
       cout << endl;
       }*///マップ確認用
    if(solve(ys-1,xs-1))cout << "OK\n";
    else cout << "NG\n";
  }
}
int solve(int xs,int ys){
  if(xs < 0 || ys < 0 || xs > w-1 || ys > h-1 || maps[ys][xs] == 0){
    return 0;
  }
  else if(maps[ys][xs] == maps[xg-1][yg-1]){
    return 1;
  }
  maps[ys][xs] = 0;
  return solve(xs+1,ys) + solve(xs,ys+1)+ solve(xs-1,ys) + solve(xs,ys-1);
}

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

int w,h;
int field[101][101];
int sx,sy;
int gx,gy;
int n;
int color;
bool ans;
void DFS(int x,int y)
{
	field[y][x] = -1;
	if(x == gx && y == gy)
		ans = true;
	if(0<=x-1){
		if(color == field[y][x-1]){
			DFS(x-1,y);
		}
	}
	if(w>x+1){
		if(color == field[y][x+1]){
			DFS(x+1,y);
		}
	}
	if(0<=y-1){
		if(color == field[y-1][x]){
			DFS(x,y-1);
		}
	}
	if(h>y+1){
		if(color == field[y+1][x]){
			DFS(x,y+1);
		}
	}
}
int main()
{
	while(cin >> w >> h){
		if(!w&&!h)
			break;
		ans = false;
		memset(field,-1,sizeof(field));
		cin >> sx >> sy;
		cin >> gx >> gy;
		cin >> n;
		for(int i=0;i<n;i++){
			int c,d,x,y;
			cin >> c >> d >> x >> y;
			if(d == 1){
				for(int i=0;i<4;i++){
					for(int j=0;j<2;j++){
						field[y+i][x+j] = c;
					}
				}
			}
			else if(d == 0){
				for(int i=0;i<2;i++){
					for(int j=0;j<4;j++){
						field[y+i][x+j] = c;
					}
				}
			}
		}
		color = field[sy][sx];
		if(color!= -1)
			DFS(sx,sy);
		if(ans)
			cout << "OK" << endl;
		else
			cout << "NG" << endl;
	}
	return 0;
}