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<string>
#include<vector>
#include<utility>
#include<queue>
#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<complex>
#define INF 2147483647
#define llINF 9223372036854775807
#define pb push_back
#define mp make_pair 
#define F first
#define S second
#define ll long long

using namespace std;
int main(){
  int w,h;
  while(cin>>w>>h,w+h){
    int xs,ys,xg,yg;
    bool Map[h+10][w+10]={};
    bool flag=false;
    cin>>xs>>ys>>xg>>yg;
    xs--;ys--;xg--;yg--;
    int n;cin>>n;
    int Map2[h+10][w+10]={};
    Map[ys][xs]=true;
    queue<pair<int,int> >que;
    que.push(mp(ys,xs));
    for(int i=0;i<n;i++){
      int c,d,x,y;
      cin>>c>>d>>x>>y;
      x--;y--;
      if(d==0){
	for(int i=y;i<y+2;i++)
	  for(int j=x;j<x+4;j++)
	    Map2[i][j]=c;
      }else if(d==1){
	for(int i=y;i<y+4;i++)
	  for(int j=x;j<x+2;j++)
	    Map2[i][j]=c;
      }
    }
    int vx[4]={0,-1,0,1};
    int vy[4]={1,0,-1,0};
    while(!que.empty()){
      pair<int,int>now=que.front();
      que.pop();
      if(now.F==yg&&now.S==xg){
	flag=true;
	break;
      }
      for(int kk=0;kk<4;kk++){
	int as=now.F+vx[kk];int bs=now.S+vy[kk];
	if(as<h&&as>=0&&bs<w&&bs>=0&&Map2[now.F][now.S]==Map2[as][bs]&&!Map[as][bs]){
	  que.push(mp(as,bs));
	  Map[as][bs]=true;
	}
      }
    }
    if(flag)
      cout<<"OK"<<endl;
    else
      cout<<"NG"<<endl;
  }
  return 0;
}

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

int w,h;
int sx,sy,gx,gy;
int n,c,d,x,y;
int g[200][200];
bool use[200][200];
int dy[] = {-1,0,1,0}, dx[] = {0,1,0,-1};

void rec(int Y,int X, char c){
  if(use[Y][X])return;
  use[Y][X] = true;

  for(int i=0;i<4;i++){
    int ny = Y+dy[i], nx = X+dx[i];
    if(ny<1 || nx<1 || ny>h || nx>w)continue;
    if(g[ny][nx] == c)rec(ny,nx,c);
  }
}

int main(){
  while(cin >> w >> h,w||h){
    for(int i=1;i<=h;i++){
      for(int j=1;j<=w;j++){
	g[i][j] = 0;
	use[i][j] = false;
      }
    }

    cin >> sx >> sy >> gx >> gy >> n;
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
      if(d==0){
	for(int j=0;j<2;j++){
	  for(int k=0;k<4;k++){
	    g[y+j][x+k] = c;
	  }
	}
      }else{
	for(int j=0;j<4;j++){
	  for(int k=0;k<2;k++){
	    g[y+j][x+k] = c;
	  }
	}
      }
    }

    if(!g[sy][sx] || !g[gy][gx] || g[sy][sx] != g[gy][gx]){
      cout << "NG\n";
    }else{
      rec(sy,sx,g[sy][sx]);
      cout << (use[gy][gx]?"OK":"NG") << endl;
    }
  }
}

C++: #include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <complex>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <iostream>
#include <map>
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-9
#define INF 2000000000
#define sz(x) ((int)(x).size())
#define fi first
#define sec second
#define SORT(x) sort((x).begin(),(x).end())
#define all(x) (x).begin(),(x).end()
#define EQ(a,b) (abs((a)-(b))<eps)
int w,h;
int sx,sy,gx,gy;
int n;
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
bool used[120][120];
int f[120][120];
void set(int c,int d,int x,int y)
{
	if(d==0)
	{
		for(int i=0;i<2;i++)
		{
			for(int j=0;j<4;j++)
			{
				f[x+i][y+j]=c;
			}
		}
	}
	else
	{
		for(int i=0;i<4;i++)
		{
			for(int j=0;j<2;j++)
			{
				f[x+i][y+j]=c;
			}
		}
	}
	return;
}
bool judge()
{
	if(f[sx][sy]!=f[gx][gy])return false;
	memset(used,false,sizeof(used));
	queue<P> q;
	q.push(mp(sx,sy));
	used[sx][sy]=true;
	while(!q.empty())
	{
		P a=q.front();
		q.pop();
		for(int i=0;i<4;i++)
		{
			int nx=a.fi+dx[i],ny=a.sec+dy[i];
			if(nx<0||nx>=h||ny<0||ny>=w)continue;
			if(used[nx][ny]||f[nx][ny]!=f[a.fi][a.sec])continue;
			if(nx==gx&&ny==gy)return true;
			used[nx][ny]=true;
			q.push(mp(nx,ny));
		}
	}
	return false;
}
int main()
{
	while(1)
	{
		memset(f,0,sizeof(f));
		scanf("%d %d",&h,&w);
		if(w==0&&h==0)break;
		scanf("%d %d",&sy,&sx);
		scanf("%d %d",&gy,&gx);
		scanf("%d",&n);
		for(int i=0;i<n;i++)
		{
			int c,d,x,y;
			scanf("%d %d %d %d",&c,&d,&y,&x);
			set(c,d,x,y);
		}
		if(judge())puts("OK");
		else puts("NG");
	}
	return 0;
}

C++: #include <iostream>
#include <cstdio>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<(n);i++)
int dy[] = {1, 0, 0, -1};
int dx[] = {0, 1, -1, 0};
int b[110][110];
int w, h;
int xs, ys, xg, yg;
int color;
bool flag = false;
bool used[110][110];

void dfs(int y, int x){
	rep(i, 4){
		int ny = y + dy[i], nx = x + dx[i];
		if(used[ny][nx]) continue;//???????????¨???????????????????????????
		if(!(0 <= ny && ny < h && 0 <= nx && nx < w)) continue;
		if(b[ny][nx] != color) continue;
		if(ny == yg && nx == xg){
			used[ny][nx] = true;
			flag = true; return;//????????????
		}
		used[ny][nx] = true;
		dfs(ny, nx);
	}
	return;//????????¢?????¨???????????????
}

int main(void){
	while(1){
		rep(i, 110)rep(j, 110){
			b[i][j] = -1; used[i][j] = false;
		}
		cin >> w >> h;
		if(w == 0 && h == 0) return 0;
		cin >> xs >> ys >> xg >> yg;
		xs--; ys--; xg--; yg--;
		int n; cin >> n;
		rep(i, n){
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			x--; y--;
			if(d == 0){//?¨?
				b[y][x] = b[y][x + 1] = b[y][x + 2] = b[y][x + 3] = c;
				b[y + 1][x] = b[y + 1][x + 1] = b[y + 1][x + 2] = b[y + 1][x + 3] = c;
			}else{//???
				b[y][x] = b[y][x + 1] = c;
				b[y + 1][x] = b[y + 1][x + 1] = c;
				b[y + 2][x] = b[y + 2][x + 1] = c;
				b[y + 3][x] = b[y + 3][x + 1] = c;
			}
		}
		color = b[ys][xs];
		if(color == -1) {//?????????????????????????????????
			printf("NG\n"); continue;
		}
		used[ys][xs] = true; flag = false;
		dfs(ys, xs);
		if(flag) printf("OK\n");
		else printf("NG\n");
	}
}