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>
#include<algorithm>
#include<string>
	using namespace std;
	int xs,ys,w,h,n,ban[111][111],xg,yg;bool visited[101][101];
	bool dfs(int x,int y,int c){
		//cout<<x<<" "<<y<<endl;
				if(c-1||ban[x][y]!=c)return false;
		if(xg==x&&yg==y)return true;
		//if(ban[xs][ys]==0)return false;
		if(ban[x+1][y]==c&&visited[x+1][y]==false){
			visited[x+1][y]=true;
			if(dfs(x+1,y,c))return true;
		}
		if(ban[x][y+1]==c&&visited[x][y+1]==false){
			visited[x][y+1]=true;
			if(dfs(x,y+1,c))return true;
		}
		if(x>=2&&ban[x-1][y]==c&&visited[x-1][y]==false){
			visited[x-1][y]=true;
			if(dfs(x-1,y,c))return true;
		}
		if(y>=2&&ban[x][y-1]=c&&visited[x][y-1]==false){
			visited[x][y-1]=true;
			if(dfs(x,y-1,c))return true;
		}
		return false;
	}


int main(){

	while(cin>>w>>h&&w&&h){
	cin>>xs>>ys>>xg>>yg>>n;
	for(int i=0;i<101;i++)
	for(int j=0;j<101;j++)ban[i][j]=-1,visited[i][j]=false;
	
	for(int i=0;i<n;i++){
		int c,d,x,y;
		cin>>c>>d>>x>>y;
		if(!d){
			for(int i=x;i<x+4;i++){
				for(int j=y;j<y+2;j++){
					ban[i][j]=c;
				}
			}
		}
		else{
		for(int i=x;i<x+2;i++){
				for(int j=y;j<y+4;j++){
					ban[i][j]=c;
				}
			}
		}
		}
		if(dfs(xs,ys,ban[xs][ys]))cout<<"OK"<<endl;
	else cout<<"NG"<<endl;
	}
	return 0;
	}

C++: #include <iostream>
using namespace std;
 
int weight, hight;
int g[101][101];
int sc;
int sx, sy, gx, gy;
bool flag = false;
const int vx[4] = {0, 0, 1, -1};
const int vy[4] = {1, -1, 0, 0};
 
void dfs(int x, int y){
    if(x == gx && y == gy){
        flag = true;
        return;
    }
    
    g[y][x] = -1;
    
    for(int i = 0;i < 4;i++){
        int nx = x + vx[i];
        int ny = y + vy[i];
         
        if(nx >= 0 && nx < weight && ny >= 0 && ny < hight && g[ny][nx] == sc){
            dfs(nx, ny);
        }
    }
    return;
}
 
int main(){ 
    while(1){
        int n, c, d, x, y;
        flag = false;
        g[101][101] = {};
        
        cin >> weight >> hight;
 
        if(weight == 0 && hight == 0){
            break;
        }
         
        cin >> sx >> sy >> gx >> gy >> n;
         
        for(int i = 0;i < n;i++){
            cin >> c >> d >> x >> y;
             
            if(d == 0){
                for(int h = 0;h < 2;h++){
                    for(int w = 0;w < 4;w++){
                        g[y+h][x+w] = c;
                    }
                }
            }else{
                for(int h = 0;h < 4;h++){
                    for(int w = 0;w < 2;w++){
                        g[y+h][x+w] = c;
                    }
                }
            }
        }
         
        sc = g[sy][sx];
        dfs(sx, sy);
         
        if(flag){
            cout << "OK" << endl;
        }else{
            cout << "NG" << endl;
        }
    }
     
    return 0;
}

C++: #include <iostream>
using namespace std;
 
int weight, hight;
int g[101][101] = {0};
int sc;
int sx, sy, gx, gy;
bool flag = false;
const int vx[4] = {0, 0, 1, -1};
const int vy[4] = {1, -1, 0, 0};
 
void dfs(int x, int y){
    if(x == gx && y == gy){
        flag = true;
        return;
    }
    
    if(g[y][x] == 0){
        flag = false;
        return;
    }
    
    g[y][x] = -1;
    
    for(int i = 0;i < 4;i++){
        int nx = x + vx[i];
        int ny = y + vy[i];
         
        if(nx >= 0 && nx < weight && ny >= 0 && ny < hight && g[ny][nx] == sc){
            dfs(nx, ny);
        }
    }
    return;
}
 
int main(){
    while(1){
        int n, c, d, x, y;
        flag = false;
        g[101][101] = {0};
        
        cin >> weight >> hight;
        
        if(weight == 0 && hight == 0){
            break;
        }
         
        cin >> sx >> sy >> gx >> gy >> n;
         
        for(int i = 0;i < n;i++){
            cin >> c >> d >> x >> y;
             
            if(d == 0){
                for(int h = 0;h < 2;h++){
                    for(int w = 0;w < 4;w++){
                        g[y+h][x+w] = c;
                    }
                }
            }else{
                for(int h = 0;h < 4;h++){
                    for(int w = 0;w < 2;w++){
                        g[y+h][x+w] = c;
                    }
                }
            }
        }
         
        sc = g[sy][sx];
        dfs(sx, sy);
         
        if(flag){
            cout << "OK" << endl;
        }else{
            cout << "NG" << endl;
        }
    }
     
    return 0;
}