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>
using namespace std;

char F[102][102];
bool MazeJudge;
int xg,yg;

char ItoC(int i){
	if(i==1){
		return '1';
	}else if(i==2){
		return '2';
	}else if(i==3){
		return '3';
	}else if(i==4){
		return '4';
	}else if(i==5){
		return '5';
	}
}

void DFS(int X,int Y,char C)
{
	if(F[X][Y]!=C)
		return;

	F[X][Y] = '.';

	if(X==xg&&Y==yg){
		MazeJudge = true;
		return;
	}
	
	DFS(X-1,Y  ,C);
	DFS(X  ,Y+1,C);
	DFS(X+1,Y  ,C);
	DFS(X  ,Y-1,C);
}
	

int main()
{
	while(true){
		for(int j=0;j<102;j++){
			for(int i=0;i<102;i++){
				F[i][j] = '0';
			}
		}

		MazeJudge = false;
		int w,h;
		cin >> w >> h;
		if(w==0&&h==0)
			break;

		int xs,ys;
		cin >> xs >> ys >> xg >> yg;

		int n;
		cin >> n;
		for(int i=0;i<n;i++){
			int c,d,x,y;
			cin >> c >> d >> x >> y;
    			char color = ItoC(c);
			if(d==0){
				F[x  ][y  ] = color;
				F[x+1][y  ] = color;
				F[x+2][y  ] = color;
				F[x+3][y  ] = color;
				F[x  ][y+1] = color;
				F[x+1][y+1] = color;
				F[x+2][y+1] = color;
				F[x+3][y+1] = color;
			}else if(d==1){
				F[x  ][y  ] = color;
				F[x+1][y  ] = color;
				F[x  ][y+1] = color;
				F[x+1][y+1] = color;
				F[x  ][y+2] = color;
				F[x+1][y+2] = color;
				F[x  ][y+3] = color;
				F[x+1][y+3] = color;		
			}
		}
		
		//デバッグ用迷路表示
		/*for(int j=0;j<102;j++){
			for(int i=0;i<102;i++){
				cout << F[i][j];
			}
			cout << endl;
		}*/

		char rc = F[xs][ys];
		DFS(xs,ys,rc);
		if(MazeJudge==true){
			cout << "OK" << endl;
		}else if(MazeJudge==false){
			cout << "NG" << endl;
		}
	}

	return 0;
}

C++: int  map[100][100];
bool visited[100][100];
int  w,h;
int  xs,ys;
int  xg,yg;
int  n;

int dfs(int x,int y) {
	static int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
	if(x==xg&&y==yg) return 1;
	visited[x][y]=true;
	for(int i=0;i<4;i++) {
		int nx=x+dx[i],ny=y+dy[i];
		if(0<=nx&&nx<w&&0<=ny&&ny<h&&map[x][y]==map[nx][ny]&&!visited[nx][ny]) {
			if(dfs(nx,ny)) return 1;
		}
	}
	return 0;
}

int main() {
	int c,d,x,y;

	while(1) {
		memset(map,0,sizeof(map));
		memset(visited,0,sizeof(visited));
		scanf("%d %d",&w,&h);
		if(w==0&&h==0) break;
		scanf("%d %d",&xs,&ys);xs--;ys--;
		scanf("%d %d",&xg,&yg);xg--;yg--;
		scanf("%d",&n);
		for(int i=0;i<n;i++) {
			scanf("%d %d %d %d",&c,&d,&x,&y);x--;y--;
			int X,Y;
			if(d==1) {
				X=2;Y=4;
			}else {
				X=4;Y=2;
			}
			for(int j=0;j<X;j++) {
				for(int k=0;k<Y;k++) {
					map[x+j][y+k]=c;
				}
			}
		}
		printf("%s\n",dfs(xs,ys)?"OK":"NG");
	}
}

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;
        }
      }
    }

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