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<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<iostream>
#include<queue>
using namespace std;
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
struct point{
    int x,y;
    point(){}
    point(int a, int b){x = a;y = b;}
};
int main(void){

    int w,h;
    while(cin>>w>>h,w){
        int xs,ys,xg,yg,n;
        cin>>xs>>ys>>xg>>yg>>n;
        int field[100][100] = {{0}};
        for(int i = 0;i < n;i++){
            int c,d,x,y;
            int dw = 4,dh = 2;
            cin>>c>>d>>x>>y;
            if(d)swap(dw,dh);
            for(int di = y;di < dh + y && di < h; di++){
                for(int dj = x;dj < dw + x && dj < w;dj++){
                    field[di][dj] = c;
                }
            }
        }
        int C = field[xs][ys];
        bool vis[100][100] = {{false}};
        queue<point> Q;
        Q.push(point(xs,ys));
        if(field[xs][ys] != C)cout<<"NG"<<endl;
        else {
            while(!Q.empty()){
                point P = Q.front();
                Q.pop();
                for(int i = 0;i < 4;i++){
                    point p = point(P.x + dx[i],P.y + dy[i]);
                    if(0 <= p.x && p.x < w && 0 <= p.y && p.y < h){
                        if(!vis[p.x][p.y]&&field[p.x][p.y] == C){

                            vis[p.x][p.y] = true;
                            Q.push(p);
                        }
                    }
                }
            }
        }
        if(vis[xg][yg])cout<<"OK"<<endl;
        else cout<<"NG"<<endl;
    }


    return 0;
}

C++: #include <set>
#include <map>
#include <list>
#include <queue>
#include <stack>
#include <cmath>
#include <ctype.h>
#include <ctime>
#include <cstdio>
#include <vector>
#include <string>
#include <bitset>
#include <cctype>
#include <cstdlib>
#include <cstring>
#include <utility>
#include <numeric>
#include <complex>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <cassert>
#include <iostream>
#include <iterator>
#include <algorithm>

using namespace std;

#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i, n) REP(i, 0, n)

//4方向ベクトル→↑←↓
int dx[] ={1,0,-1,0};
int dy[] ={0,-1,0,1};
//ブロック2×4 
int w,h;//ボードの横,縦
int xs,ys;//スタートの座標
int xg,yg;//ゴールの座標
int n;//ブロックの個数
int c,d;//ブロックの色,ブロックの向き,ブロックの位置x,y

int board[102][102];

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

int main(){
  while(scanf("%d %d",&w,&h)){
    if(w==0&&h==0)
      break;
    cin>>xs>>ys>>xg>>yg>>n;
    for(int i = 0;i < n;i++){
      int x,y;
      cin >>c>>d>>x>>y;
      int W,H;
      if(d ==0){
	W =4;
	H =2;
      }else{
	W = 2;
	H = 4;
      }
      for(int i = 0;i < H;i++){
	for(int j = 0;j < W;j++){
	  board[j+x][i+y] =c;
	}
      }
  }
    cout<<((dfs(xs,ys,board[xs][ys]))?"OK":"NG")<<endl;
  }
  return 0;
}

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

int F[102][102] = { 0 };

void DFS(int Y, int X, int c) {
	//cout << Y << " " << X << endl;
	if (F[Y][X] != c || c != 0)
		return;
	F[Y][X] = 10;
	DFS(Y - 1, X, c);//???
					 //DFS(Y - 1, X+1, A_ito);//??????
	DFS(Y, X + 1, c);//???
					 //DFS(Y + 1, X+1, A_ito);//??????
	DFS(Y + 1, X, c);//???
					 //DFS(Y + 1, X-1, A_ito);//??????
	DFS(Y, X - 1, c);//???
					 //DFS(Y - 1, X-1, A_ito);//??????
}


int main()
{
	int xs, ys, xg, yg, n;
	int c, d, x, y;
	int W = 1, H = 1;

	while ((W != 0) && (H != 0)) {
		cin >> W >> H;
		cin >> xs >> ys >> xg >> yg >> n;
		for (int i = 1;i <= n;i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				F[x][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y] = c;
				F[x + 1][y + 1] = c;
				F[x + 2][y] = c;
				F[x + 2][y + 1] = c;
				F[x + 3][y] = c;
				F[x + 3][y + 1] = c;
			}
			if (d == 1) {
				F[x][y] = c;
				F[x + 1][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y + 1] = c;
				F[x][y + 2] = c;
				F[x + 1][y + 2] = c;
				F[x][y + 3] = c;
				F[x + 1][y + 3] = c;
			}
		}
		if (F[ys][xs] != 0)
			DFS(ys, xs, F[ys][xs]);

		if (F[yg][xg] == F[ys][xs]) {
			cout << "OK" << endl;
		}
		else { cout << "NG" << endl; }
		for (int i = 0;i < H;i++) {
			for (int j = 0;j < W;j++) {
				F[i][j] = 0;
			}
		}
		
	}

	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int bord[101][101]={},playx[2],playy[2];
int movex[]={1,0,-1,0},movey[]={0,1,0,-1};
int serch(int x,int y,int color)
{
    if(color==0)return 0;
    int now=0;
    bord[y][x]=0;
    if(x==playx[1]&&y==playy[1])return 1;
    for(int i=0;i<4&&now==0;i++)
        if(bord[movey[i]+y][movex[i]+x]==color)now=serch(movex[i]+x,movey[i]+y,color);
    return now;
}
int main()
{
    int  h,w;
    while(cin>>h>>w,h,w){
        for(int i=0;i<=h+1;i++){
                for(int j=0;j<=w+1;j++)bord[i][j]=0;
        }
        for(int i=0;i<2;i++)cin>>playx[i]>>playy[i];
        int n;
        cin>>n;
        for(int i=0,co,mu,x,y;i<n;i++){
            cin>>co>>mu>>x>>y;
            for(int j=0;j<4;j++){
                if(mu==1){
                    bord[y+j][x]=co;
                    bord[y+j][x+1]=co;
                }
                else{
                    bord[y][x+j]=co;
                    bord[y+1][x+j]=co;
                }
            }
        }
        if(serch(playx[0],playy[0],bord[playy[0]][playx[0]]))cout<<"OK\n";
        else cout<<"NG\n";
    }
}