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<stdio.h>
#include<string.h>
#include<queue>
#include<utility>
using namespace std;
char m[128][128];
void PutSquare(int x, int y, int c)
{
	m[y][x] = m[y+1][x] = m[y+1][x+1] = m[y][x+1] = static_cast<char>(c);
}
bool CanReach(int sx,int sy,int gx,int gy)
{
	bool f[128][128]={};

	typedef pair<int,int>P;
	queue<P>q;
	q.push(P(sx,sy));

	const char c = m[sy][sx];
	if(!c)
		return false;
	const int dx[]={0,1,0,-1},dy[]={1,0,-1,0};
	while(!q.empty())
	{
		P p = q.front();
		q.pop();
		if(f[p.second][p.first] || c!=m[p.second][p.first])
			continue;
		if(p.first==gx && p.second==gy)
			return true;
		f[p.second][p.first] = true;
		for(int i=0; i<4; ++i)
			q.push(P(p.first+dx[i],p.second+dy[i]));
	}
	return false;
}
int main()
{
	int h, w;
	int sx, sy;
	int gx, gy;
	int n;
	int c, d, x, y;
	while(scanf("%d%d",&w,&h),h)
	{
		memset(m,0,sizeof(m));

		scanf("%d%d",&sx,&sy);
		scanf("%d%d",&gx,&gy);
		scanf("%d",&n);
		while(n--)
		{
			scanf("%d%d%d%d",&c,&d,&x,&y);
			PutSquare(x,y,c);
			if(d==0)
				PutSquare(x+2,y,c);
			else
				PutSquare(x,y+2,c);
		}
		puts(CanReach(sx,sy,gx,gy) ? "OK" :"NG");
	}
	return 0;
}

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

int weight, hight;
int g[110][110];
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;
    }

    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){
            g[y][x] = 8;
            dfs(nx, ny);
        }
    }
}

void disp(){
    for(int i = 0;i < hight;i++){
        for(int j = 0;j < weight;j++){
            cout << g[i][j];
        }cout << endl;
    }
}

int main(){
    int dn, c, d, x, y;
    
    while(cin >> weight >> hight){
        if(weight == 0 && hight == 0){
            break;
        }
        
        cin >> sx >> sy >> gx >> gy >> dn;
        
        for(int i = 0;i < dn;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];
        flag = false;
        dfs(sx, sy);
        
        if(flag){
            cout << "OK" << endl;
        }else{
            cout << "NG" << endl;
        }
    }
    
    return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<string>
using namespace std;
int w,h,xs,ys,xg,yg,n,ban[111][111]={{0},{0}};
bool visited [101][101];
const int START=4545191;
const int GOAL=454545;

	bool dfs(int x,int y){
		//cout<<x<<" "<<y<<endl;
		if(xg==x&&yg==y)return true;
		
		if(ban[x+1][y]==ban[xs][ys]&&visited[x][y]==false){
			visited[x][y]=true;
			if(dfs(x+1,y))return true;
		}
		if(ban[x][y+1]==ban[xs][ys]&&visited[x][y]==false){
			visited[x][y]=true;
			if(dfs(x,y+1))return true;
		}
		if(x>=2&&ban[x-1][y]==ban[xs][y]&&visited[x][y]==false){
			visited[x][y]=true;
			if(dfs(x-1,y))return true;
		}
		if(y>=2&&ban[x][y-1]==ban[xs][y]&&visited[x][y]==false){
			visited[x][y]=true;
			if(dfs(x,y-1))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]=0,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))cout<<"OK"<<endl;
	else cout<<"NG"<<endl;
	}
	return 0;
	}

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

void DFScolor(int X,int Y,int color,int Xg,int Yg){

	if(F[X][Y]!=color)
		return;
	
	F[X][Y]=9;
	DFScolor(X-1,Y,color,Xg,Yg);
	DFScolor(X,Y+1,color,Xg,Yg);
	DFScolor(X+1,Y,color,Xg,Yg);
	DFScolor(X,Y-1,color,Xg,Yg);
	
}


int main(){
while(1){
	int H,W,xg,yg,xs,ys,n,count=0;
	cin>>H;
	if(H==0)
		count++;
	cin>>W;
	if(W==0)
		count++;
	if(count==2)
		return 0;
	cin>>xs>>ys;
	cin>>xg>>yg;	
	cin>>n;
	int c,d,x,y;
	int xb[n],yb[n],colo[n];
	for(int i=0;i<n;i++){
		
		cin>>c>>d>>x>>y;
		colo[i]=c;
		xb[i]=x;
		yb[i]=y;
		if(d==0){
			for(int o=y;o<y+2;o++){
				for(int j=x;j<x+4;j++){
					F[j][o]=c;
				}
			}
		}
		else if(d==1){
			for(int o=y;o<y+4;o++){
				for(int j=x;j<x+2;j++){
					F[j][o]=c;
				}
			}
		}
		
	}
	
	for(int i=0;i<n;i++){
		if(xb[i]==xs&&yb[i]==ys){
			DFScolor(xb[i],yb[i],colo[i],xg,yg);
			
			break;
		}
	}
	if(F[xg][yg]==9)
		cout<<"OK"<<endl;
	else
		cout<<"NG"<<endl;
	
}
	return 0;
}