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++: 
//インクルード文
#include <iostream>
#include <stack>
#include <vector>
#include <stdlib.h>
#include <cstdio>
#include <string>
//#include <assert.h>

//:std省略
using namespace std;

//グローバル変数
int f[1000][1000];

//マクロ指定
#define fc f[x + j][y + l] = c

//深さ優先探索( dfs = Depth - First Search )
void dfs(int a, int b, int c) {

	if (f[a][b] == c) {


		f[a][b] = 10;
		dfs(a + 1, b, c);
		dfs(a - 1, b, c);
		dfs(a, b + 1, c);
		dfs(a, b - 1, c);


	}

//	else return;

}

//メイン文
int main(){

	int w, h, n = 0;
	int i, j, l;
	int xs, ys; 
	int xg, yg;

	const int cnt = w + h;

	for(;;) {
		cin >> w >> h;

		
		if ( cnt == 0) break;
		
		for (i = 1; i <= h; ++i) {
			for (j = 1; j <= w; ++j) {
				f[i][j] = -1;
			}
		}

		cin >> xs >> ys;
		cin >> xg >> yg;
		cin >> n;

		for (i = 0; i < n; ++i) {
			int c, d, x, y;

			cin >> c >> d;
			cin >> x >> y;

			if (d == 0) {
				for (j = 0; j < 4; ++j) {
					for (l = 0; l < 2; ++l) {
						fc;
					}
				}
			}

			else {//d==1

				

				for (j = 0; j < 2; ++j) {
					for (l= 0; l < 4; ++l) {
						fc;
					}
				}
			}
		}
/*

			if (d == 0) {
				for (j = 0; j < 2; ++j) {
					for (l = 0; l < 4; ++l) {
						f[x + j][y + l] = c;
					}
				}
			}

			else {
				for (j = 0; j < 4; ++j) {
					for (l= 0; l < 2; ++l) {
						f[x + j][y + l] = c;
					}
				}
			}	
		}

*/


		dfs(xs, ys, f[xs][ys]);


//		char gg = 'OK';
//		char ggwp = 'NG';


		

		if (f[xg][yg] == 10) printf("OK\n");

		else 		         printf("NG\n");



			//			assert(i == 10);
			//			assert(i = 9);
			//			assert(i = 8);
			//			assert(i = 7);
			//			assert(i = 6);
			//			assert(i = 5);
			//			assert(i = 4);
			//			assert(i = 3);
			//			assert(i = 2);
			//			assert(i = 1);

		


	}
	return 0;
}

/*


20 20
1 1
9 9
7
2 0 1 1
5 1 1 3
2 1 3 3
1 1 5 2
5 1 7 3
2 0 2 7
2 0 6 8
20 20
9 9
1 1
6
2 0 1 1
1 0 5 1
2 1 1 3
5 0 1 7
3 1 5 5
4 1 8 5
0 0


*/

C++: #include <iostream>
using namespace std;
   
int F[102][102];
int xg,yg,w,h;
   
   
void DFS(int Y,int X,int c){
  //if(Y < 1 || X < 1)
    //return;
  if(F[Y][X] != c){
    return;
  }
   
  F[Y][X] = -1;
  DFS(Y+1,X  ,c);
  DFS(Y-1  ,X,c);
  DFS(Y,X+1  ,c);
  DFS(Y  ,X-1,c);
}
   
   
int main(){
  int 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] = 10;
      }
    }
       F[0][-1] = 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(c == 0)
         c = 1919810;
      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 <iostream>
using namespace std;

int C[102][102];
int ans;
int xg,yg;

void meiro(int W,int H,int c){
 if(W==xg && H==yg){
   ans = 1;
   return;
 }

 if(C[W][H]!=c){
   return;
 }

 C[W][H] = '.';

 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;
   }

   int xs,ys;
   cin >> xs >> ys;

   cin >> xg >> yg;

   int n;
   cin >> n;
   int c[n],d[n],x[n],y[n];

   int cbase;

   for(int i=0;i<n;i++){
     cin >> c[i] >> d[i] >> x[i] >> y[i];

     if(d[i]==0){
       for(int j=x[i];j<x[i]+4;j++){
         for(int k=y[i];k<y[i]+2;k++){
           C[j][k]=c[i];
         }
       }
     }
     if(d[i]==1){
       for(int j=x[i];j<x[i]+2;j++){
         for(int k=y[i];k<y[i]+4;k++){
           C[j][k]=c[i];
         }
       }
     }

     if(x[i]==1 &&y[i]==1){
       cbase = c[i];
     }
   }
   ans = 0;
if(cbasew == 0){
 cout << "NG"<<endl;
 continue;
}
   meiro(xs,ys,cbase);

   if(ans==1){
     cout << "OK" << endl;
   }else{
     cout << "NG" << endl;
   }
 }

 return 0;
}

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

const int size = 110;
int board[size][size];
int visited[size][size];
int xblocks[2][8] = { {0, 1, 2, 3, 0, 1, 2, 3},
		      {0, 0, 0, 0, 1, 1, 1, 1} };
int yblocks[2][8] = { {0, 0, 0, 0, 1, 1, 1, 1},
		      {0, 1, 2, 3, 0, 1, 2, 3} };
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};

int main() {
  int w,h,xs,ys,xg,yg,n,c,d,x,y;
  while(cin>>w>>h, w|h) {
    for(int i=0; i<size; ++i)
      for(int j=0; j<size; ++j) {
	board[i][j] = 0;
	visited[i][j] = 0;
      }

    cin>>xs>>ys;
    cin>>xg>>yg;
    cin>>n;
    for(int i=0; i<n; ++i) {
      cin>>c>>d>>x>>y;
      for(int j=0; j<8; ++j)
	board[x+xblocks[d][j]][y+yblocks[d][j]] = c;
    }

    queue<pair<int,int> > Q;
    Q.push(pair<int,int>(xs,ys));
    while(!Q.empty()) {
      pair<int,int> pos = Q.front(); Q.pop();
      int nx = pos.first,ny = pos.second;
      if(visited[ny][nx]) continue;
      visited[ny][nx] = 1;
      if(nx == xg && ny == yg) {
	cout<<"OK"<<endl;
	goto NEXT;
      }

      for(int i=0; i<4; ++i) {
	if(nx+dx[i] >= 0 && nx+dx[i] <= w &&
	   ny+dy[i] >= 0 && ny+dy[i] <= h &&
	   board[ny][nx] == board[ny+dy[i]][nx+dx[i]])
	  Q.push(pair<int,int>(nx+dx[i],ny+dy[i]));
      }
      board[ny][nx] = -1;
    }
    cout<<"NG"<<endl;
  NEXT:
    ;
  }
}