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 <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <ctime>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <numeric>
#include <cassert>
using namespace std;
static const double EPS = 1e-10;
typedef long long ll;
#define rep(i,n) for(int i=0;i<n;i++)
#define rev(i,n) for(int i=n-1;i>=0;i--)
#define all(a) a.begin(),a.end()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define SS stringstream
#define DBG1(a) rep(_X,sz(a)){printf("%d ",a[_X]);}puts("");
#define DBG2(a) rep(_X,sz(a)){rep(_Y,sz(a[_X]))printf("%d ",a[_X][_Y]);puts("");}
#define bitcount(b) __builtin_popcount(b)
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)

#define delete(a,n) a.erase(remove(all(a),n),a.end())
template<typename T, typename S> vector<T>& operator<<(vector<T>& a, S b) { a.push_back(b); return a; }
template<typename T> void operator>>(vector<T>& a, int b) {while(b--)if(!a.empty())a.pop_back();}
bool isprime(int n){ if(n<2)return false;  for(int i=2;i*i<=n;i++)if(n%i==0)return false;  return true;} 
ll b_pow(ll x,ll n){return n ? b_pow(x*x,n/2)*(n%2?x:1) : 1ll;}
string itos(int n){stringstream ss;ss << n;return ss.str();}

int W,H;

int field[110][110];
int done[110][110];
int dfs(int x,int y,int gx,int gy,int col){
	if(x < 0 || y < 0 || field[y][x] == 0 || field[y][x] != col) return 0;
	if( x == gx && y == gy ){
		return 1;
	}
	if(done[y][x]) return false;
	else done[y][x] = true;
	if( dfs(x+1,y,gx,gy,col) ) return true;
	if( dfs(x-1,y,gx,gy,col) ) return true;
	if( dfs(x,y+1,gx,gy,col) ) return true;
	if( dfs(x,y-1,gx,gy,col) ) return true;
	
	
}
int main(){
	ios_base::sync_with_stdio(false);
	while(cin >> W >> H && W){
		for(int i = 0 ; i < 110 ; i++)
			for(int j = 0 ; j < 110 ; j++) 
				field[i][j] = done[i][j] = 0;
		int sx,sy,gx,gy,n;
		cin >> sx >> sy >> gx >> gy >> n;
		//sx--,sy--;
		//gx--,gy--;
		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 = 0 ; i < 3 ; i++)
					for(int j = 0 ; j < 4 ; j++)
						field[y+i][x+j] = c;
			}else{
				for(int i = 0 ; i < 4 ; i++)
					for(int j = 0 ; j < 3 ; j++)
						field[y+i][x+j] = c;
			}
		}
		/*for(int i = 0 ; i < H ; i++){
			for(int j = 0 ; j < W ; j++) cout << field[i][j];
			cout << endl;
		}*/
		cout << (dfs(sx,sy,gx,gy,field[sy][sx])?"OK":"NG") << endl;
	}
	
}

C++: #define _USE_MATH_DEFINES
#include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<climits>
#include<map>
#include<string>
using namespace std;

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

struct Data{
	int y, x;
	Data(){}
	Data(int _y, int _x){
		y = _y; x = _x;
	}
};

int fld[100][100];

void PaintFld(int c, int x, int y, int w, int h){
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			fld[y + i][x + j] = c;
		}
	}
}

int main(){
	int W, H;
	while(cin >> W >> H, W || H){
		int Xs, Ys, Xg, Yg, N, C, D, X, Y;
		cin >> Xs >> Ys >> Xg >> Yg >> N;
		for(int i = 0; i < N; i++){
			cin >> C >> D >> X >> Y;
			if(D == 0) PaintFld(C, X, Y, 4, 2);
			else PaintFld(C, X, Y, 2, 4);
		}

		queue<Data> q;
		Data q_front;
		bool memo[100][100] = {}, ans = false;
		q.push( Data(Xs, Ys) );
		while( !q.empty() ){
			q_front = q.front(); q.pop();

			if(q_front.y == Yg && q_front.x == Xg){
				ans = true; break;
			}

			if(memo[q_front.y][q_front.x]) continue;
			memo[q_front.y][q_front.x] = true;

			for(int i = 0; i < 4; i++){
				int ny = q_front.y + dy[i];
				int nx = q_front.x + dx[i];

				if(ny < 0 || H <= ny || nx < 0 || W <= nx || fld[ny][nx] != fld[Ys][Xs])
					continue;
				q.push( Data(ny, nx) );
			}
		}

		if(ans) puts("OK");
		else puts("NG");
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
 
int C[102][102];
 
void meiro(int W,int H,int c){
  if(C[W][H]!=c){
    return;
  }
 
  C[W][H] = -1;
 
  meiro(W-1,H  ,c);
  meiro(W  ,H+1,c);
  meiro(W+1,H  ,c);
  meiro(W  ,H-1,c);
}
 
int main(){
  while(1){
    int w,h;
    cin >> w >> h;
    if(w==0 && h==0){
      break;
    }
 
    for(int i=0;i<102;i++){
      for(int j=0;j<102;j++){
        C[i][j] = 10;
      }
    }
 
    int xs,ys,xg,yg;
    cin >> xs >> ys >> xg >> yg;
 
    int n;
    cin >> n;
 
    int c,d,x,y;
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
 
      if(d==0){
        for(int j=x;j<x+4;j++){
          for(int k=y;k<y+2;k++){
            C[j][k]=c;
          }
        }
      }else{
        for(int j=x;j<x+2;j++){
          for(int k=y;k<y+4;k++){
            C[j][k]=c;
          }
        }
      }
    }
 
    meiro(xs,ys,C[xs][ys]);
 
    if(C[xg][yg] == -1){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }
 
  return 0;
}