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 <bits/stdc++.h>
using namespace std;

int board[105][105];
int xg , yg;
int w, h;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
int sc;
bool b;

void dfs(int x , int y){
	if(x==xg&&y==yg) {b=true;return;}
	for(int i=0;i<4;++i){
		int tx=x+dx[i];
		int ty=y+dy[i];
		if(tx<0||ty<0||tx>=w||ty>=h) continue;
		if(board[tx][ty]!=sc || board[tx][ty]==0) continue;
		if(b) continue;
		dfs(tx,ty);
	}
}

int main(){
	while(cin >> w >> h , w||h){
		int xs , ys;
		int n;
		b=false;
		//memset(board,0,sizeof(board));
		for(int i=0;i<105;++i){
			for(int j=0;j<105;++j){
				board[j][i]=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 k=0;k<2;++k){
					for(int j=0;j<4;++j){
						board[x+j][y+k]=c;
					}
				}
			} else if(d==1){
				for(int k=0;k<4;++k){
					for(int j=0;j<2;++j){
						board[x+j][y+k]=c;
					}
				}
			}
		}
		sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {}
		else dfs(xs,ys);
		cout << ( b ? "OK" : "NG") << endl;
	}
	return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <cmath>
#include <ctime>
#include <cassert>
#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <deque>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <bitset>
#include <iterator>
#include <functional>
#include <utility>
#include <algorithm>
#include <numeric>
#include <typeinfo>
 
using namespace std;
 
#define dump(n) cout<<"# "<<#n<<"="<<(n)<<endl
#define repi(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,n) repi(i,0,n)
#define iter(c) __typeof((c).begin())
#define foreach(i,c) for(iter(c) i=(c).begin();i!=(c).end();++i)
#define allof(c) (c).begin(),(c).end()
#define mp make_pair
 
typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<string> vs;
typedef pair<int,int> pii;
 
bool solve(vvi& field,int x,int y,int xg,int yg,int c)
{
    if(field[y][x]==0)
        return false;
    if(field[y][x]!=c)
        return false;
    if(x==xg && y==yg)
        return true;
    field[y][x]=-1;
    bool res=0;
    res|=solve(field,x-1,y,xg,yg,c);
    res|=solve(field,x+1,y,xg,yg,c);
    res|=solve(field,x,y-1,xg,yg,c);
    res|=solve(field,x,y+1,xg,yg,c);
    return res;
}
 
int main()
{
    for(int w,h;cin>>w>>h,w|h;){
        int xs,ys,xg,yg,n; cin>>xs>>ys>>xg>>yg>>n;
        vvi field(110,vi(110));
        rep(k,n){
            int c,d,x,y; cin>>c>>d>>x>>y;
            if(d)
                rep(i,4) rep(j,2)
                    field[y+i][x+j]=c;
            else
                rep(i,2) rep(j,4)
                    field[y+i][x+j]=c;
        }
        cout<<(solve(field,xs,ys,xg,yg,field[ys][xs])?"OK":"NG")<<endl;
    }
     
    return 0;
}

C++: #include <iostream>
using namespace std;
  
int F[102][102];
  
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,xg,yg,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;
        }
      }
    }

  if(F[xs][ys] == 0){
    cout << "NG" << endl;
  } else {
    DFS(xs,ys,F[xs][ys]);
  
    if(F[xg][yg] == -1){
      cout << "OK" << endl;
    } else {
      cout << "NG" <<endl;
    }
  }

}
}