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;

int F[102][102];
int xg,yg,ok;

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

	

	if(X==xg&&Y==yg){
		cout << "OK"<<endl;
		ok++;
	}

	F[X][Y]=-1;

	Maze(X-1,Y  ,C);
	Maze(X  ,Y+1,C);
	Maze(X+1,Y  ,C);
	Maze(X  ,Y-1,C);
	
}



int main(){	
	while(1){
		ok=0;

		int w,h,xs,ys,n,c,d,x,y;

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

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


		for(int i=1; i<=w; i++)
			for(int j=1; j<=h; j++)
				F[j][i]=0;

		for(int i=1; i<=w;i++){
				F[w+1][i]=6;
				F[0][i]=6;
		}
		for(int i=1; i<=h;i++){
				F[i][h+1]=6;
				F[i][0]=6;
		}

		int N=0;
		while(N<n){
			cin >>c>>d>>x>>y;

			if(d){
				for(int i=x; i<x+2; i++)
					for(int j=y; j<y+4; j++){
						F[i][j]=c;
				}
			}else{
				for(int i=x; i<x+4; i++)
					for(int j=y; j<y+2; j++){
						F[i][j]=c;
					}
			}
			N++;
		}

/*for(int i=0; i<=h+1; i++){
	for(int j=0; j<=w+1; j++){
		cout <<F[j][i];
		}
	cout << endl;
}*/
		
		Maze(xs,ys,F[xs][ys]);

		if(ok==0)
			cout <<"NG"<<endl;

	}

}

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

bool dfs(int x,int y);
int w,h;
int xs,ys;
int xg,yg;
int board[111][111];
int cheak[111][111];
int xd[]={0,-1,0,1};
int yd[]={-1,0,1,0};
int main(){
  int n;
  int c,d,x,y;
  int a[]={1,0,1,0,1,0,1};
  int b[]={0,1,1,2,2,3,3};
  while(1){
    cin >> w >> h;
    if(w==0 && h==0) break;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	board[i][j]=0;
	cheak[i][j]=0;
	cout << board[i][j];
      }
      cout << endl;
    }
    cin >> xs >> ys;
    cin >> xg >> yg;
    cin >> n;
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
      board[y-1][x-1]=c;
      for(int j=0;j<7;j++){
	if(d==0) board[y+a[j]-1][x+b[j]-1]=c;
	else board[y+b[j]-1][x+a[j]-1]=c;
      }
    }
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	cout << board[i][j];
      }
      cout << endl;
    }
    if(board[ys][xs]!=0){
      if(dfs(xs-1,ys-1)==true) cout << "OK" << endl;
      else cout << "NG" << endl;
    }
    else cout << "NG" << endl;
  }
}

bool dfs(int x,int y){
  cheak[y][x]=1;
  if(x==xg-1 && y==yg-1) return true;
  for(int i=0;i<4;i++){
    int xn=x+xd[i];
    int yn=y+yd[i];
    if(xn>=0 && xn<w && yn>=0 && yn<h && board[yn][xn]==board[ys][xs] && cheak[yn][xn]==0){
      if(dfs(xn,yn)==true) return true;
    }
  }
  return false;
}

C++: #include <bits/stdc++.h>

using namespace std;

#define all(c) (c).begin(), (c).end()
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int w, h;
int xs, ys;
int xg, yg;
int maze[102][102];

using P = pair<int, int>;
void solve() {
    int c = maze[ys][xs];
    queue<P> que;
    que.push(P(ys, xs));
    set<P> visited;
    visited.insert(P(ys, xs));
    bool ok = false;
    while (que.size()) {
        auto p = que.front();
        que.pop();
        int y = p.first;
        int x = p.second;
        if (yg == y && xg == x) ok = true;
        rep(k, 4) {
            int ny = y + dy[k];
            int nx = x + dx[k];
            if (ny < 0 || nx < 0) continue;
            if (h <= ny || w <= nx) continue;
            if (maze[ny][nx] != c) continue;
            if (visited.count(P(ny, nx))) continue;
            visited.insert(P(ny, nx));
            que.push(P(ny, nx));
        }
    }
    cout << (ok ? "OK" : "NG") << endl;
}

int main() {
    while (cin >> w >> h, w) {
        rep(i, 102) rep(j, 102) maze[i][j] = -1;
        cin >> xs >> ys;
        cin >> xg >> yg;
        xs--, ys--;
        xg--, yg--;
        int n;
        cin >> n;
        rep(_, n) {
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            x--, y--;
            if (d == 0) {
                rep(i, 2) rep(j, 4) maze[y + i][x + j] = c;
            } else {
                rep(i, 4) rep(j, 2) maze[y + i][x + j] = c;
            }
        }
        solve();
    }

    return 0;
}

C++: #include <iostream>
using namespace std;
 
int F[105][105];
int xg,yg;
 
 
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,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;
        }
      }
    }
if(F[xs][ys]==0){
      cout << "NG" << endl;
      continue;
    }
  DFS(xs,ys,F[xs][ys]);
 
  if(F[xg][yg] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}