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<cstring>

using namespace std;

typedef pair<int,int> P;
const int MAX = 120;

int maze[MAX][MAX];
bool come[MAX][MAX];
P s,g;
int W,H,c;
int dx[4] = {1,0,0,-1};
int dy[4] = {0,1,-1,0};

void init(){
  memset(come,false,sizeof(come));
  memset(maze,0,sizeof(maze));
}


void input_B(){
  int n;
  cin >> n;
  while(n--){
    int c,d,x,y;
    cin >> c >> d >> x >> y;
    if(d){
      for(int i = y; i < y+4; i++)
	for(int j = x; j < x+2; j++)
	  maze[i][j] = c;
    }else{
      for(int i = y; i < y+2; i++)
	for(int j = x; j < x+4; j++)
	  maze[i][j] = c;
    }
  }
}


void solve(P p){
  
  if(come[p.second][p.first] == false){
    come[p.second][p.first] = true;
    for(int i = 0; i < 4; i++)
      if(0 < p.first+dx[i] && p.first+dx[i] <= W &&
	 0 < p.second+dy[i] && p.second+dy[i] <= H &&
	 maze[p.second][p.first] == c) solve(P(p.first+dx[i],p.second+dy[i]));
  }
}

void print(){
  for(int i = 1; i < H; i++){
    for(int j = 1; j < W; j++)// cout << come[i][j];
      cout << maze[i][j];
    cout << endl;
  }

}


int main(){
  while(cin >> W >> H && W+H){
    init();
    cin >> s.first >> s.second;
    cin >> g.first >> g.second;
    input_B();
    c = maze[s.second][s.first];
    solve(s);
    //print();
    if(come[g.second][g.first] && c) cout << "OK" << endl;
    else cout << "NG" << endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int board[102][102];
int xg , yg;
int w, h;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
int sc;
bool b;

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

int main(){
	while(cin >> w >> h , w||h){
		int xs , ys;
		int n;
		b=false;
	        memset(board,0,sizeof(board));
		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 k=0;k<2;++k){
					for(int j=0;j<4;++j){
						board[x+j][y+k]=c;
					}
				}
			} else if(d==1){
				for(int k=0;k<4;++k){
					for(int j=0;j<2;++j){
						board[x+j][y+k]=c;
					}
				}
			}
		}
		sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {}
		else dfs(xs,ys);
		cout << ( b ? "OK" : "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;
	
}
}

C++: #include <iostream>
struct point{
	int x;
	int y;
};
int m[101][101] = {0};
int w,h,r;
point gp;
void dfs(int x,int y,int c){
	if(!(x-gp.x)&&!(y-gp.y))r=1;
	if(x>0&&m[x-1][y]==c)m[x-1][y]=0,dfs(x-1,y,c);
	if(x<w&&m[x+1][y]==c)m[x+1][y]=0,dfs(x+1,y,c);
	if(y>0&&m[x][y-1]==c)m[x][y-1]=0,dfs(x,y-1,c);
	if(y<h&&m[x][y+1]==c)m[x][y+1]=0,dfs(x,y+1,c);
	return ;
}

int main(){
	//whÍ{[hÌå«³AnÍubNÌÂ
	int n,c,d;
	//spÍX^[gn_ÌÀWAgpÍS[n_ÌÀW
	point sp,bp;
	
	while(1){
		for(int y=0;y<101;y++){
			for(int x=0;x<101;x++){
				m[x][y] = 0;
			}
		}
		r=0;
		std::cin>>w>>h;
		if(!w&&!h)return 0;
		std::cin>>sp.x>>sp.y;
		std::cin>>gp.x>>gp.y;
		std::cin>>n;
		for(int i=0;i<n;i++){
			std::cin>>c>>d>>bp.x>>bp.y;
			int bw,bh;
			d?bw=2,bh=4:bh=2,bw=4;
			for(int y=bp.y;y<=bp.y+bh;y++){
				for(int x=bp.x;x<=bp.x+bw;x++){
					m[x][y] = c;
				}
			}
		}
		if(m[sp.x][sp.y])dfs(sp.x,sp.y,m[sp.x][sp.y]),m[sp.x][sp.y] = 0;
		if(r)std::cout<<"OK"<<std::endl;
		else{std::cout<<"NG"<<std::endl;}
	}
}

C++: #include<iostream>
using namespace std;
#define MAX 105

int map[MAX][MAX];
int xs, ys, xg, yg;
int n;
int w, h;
int c, d, x, y;
int count = 0;
int color;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

void jadge(int x, int y){
	if(count == 0){
		if(0 <= x && x <= w && 0 <= y && y <= h && map[x][y] == color){
			map[x][y] = 9;
			if(x == xg && y == yg){
				count = 1;
				return;
			}
			for(int i=0; i < 4; i++){
				jadge(x+dx[i], y+dy[i]);
			}
		}
	}
}
int main(){
	while(1){
		count = 0;

		for(int i=0; i < MAX; i++){
			for(int j=0; j< MAX; j++){
				map[i][j] = 0;
			}
		}

		cin >> w >> h;
		if(w == 0 && h == 0) break;

		cin >> ys >> xs;
		cin >> yg >> xg;
		xs--; ys--; xg--; yg--;
		cin >> n;
		for(int i=0; i < n; i++){
			cin >> c >> d >> y >> x;

			for(int i=0;  i < 4; i++){
				for(int j=0; j < 2; j++){
					if(d == 1){
						map[x-1+i][y-1+j] = c;
					}
					else{
						map[x-1+j][y-1+i] = c;
					}
				}
			}
		}
		/*
		for(int i=0; i < w; i++){
			for(int j=0; j < h; j++){
				cout << map[i][j];
			}
			cout << endl;
		}
		*/
		if(map[xs][ys] != map[xg][yg]){
			cout << "NG" << endl;
			continue;
		}
		else if(map[xs][ys] == 0 || map[xg][yg] == 0){
			cout << "NG" << endl;
			continue;
		}
		color = map[xs][ys];

		jadge(xs, ys);

		if(count == 1) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
	return 0;
}