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<vector>
#include<string>
#define ll long long
#define loop(i,n) for (int i = 0; i < n; i++)
#define loops(i,f,n) for (int i = (f); i < n; i++)
#define INF 100000000000000
#define sort(a) sort(a.begin(),a.end())
#define rsort(a) sort(a.rbegin(),a.rend())
using namespace std;
int w, h, sx, sy, gx, gy, n;
vector <vector<int > > grid;
vector <vector<bool > > grid_visited;
void input(int c, int d, int x, int y)
{
	if (d == 0)//yokonaga
	{
		loop(i, 2)
		{
			loop(j, 4)
			{
				grid[y + i][x + j] = c;
			}
		}
	}
	else//tatenaga
	{
		loop(i, 4)
		{
			loop(j, 2)
			{
				grid[y + i][x + j] = c;
			}
		}
	}
}
bool a = false;
bool dfs(int nx, int ny)
{
	if (nx == gx&&ny == gy)return true;
	if (nx < 0 || ny < 0 || nx >= h || ny >= w || grid[nx][ny] == 0 || grid_visited[nx][ny])return false;
	grid_visited[nx][ny] = true;
	if ((nx + 1) >= 0 && ny >= 0 && (nx + 1) < h && ny < w)if (grid[nx + 1][ny] == grid[nx][ny])a |= dfs(nx + 1, ny);
	if (nx >= 0 && (ny + 1) >= 0 && nx < h && (ny + 1) < w)if (grid[nx][ny + 1] == grid[nx][ny])a |= dfs(nx, ny + 1);
	if ((nx - 1) >= 0 && ny >= 0 && (nx - 1) < h && ny < w)if (grid[nx - 1][ny] == grid[nx][ny])a |= dfs(nx - 1, ny);
	if (nx >= 0 && (ny - 1) >= 0 && nx < h && (ny - 1) < w)if (grid[nx][ny - 1] == grid[nx][ny])a |= dfs(nx, ny - 1);
	//return (dfs(nx + 1, ny) || dfs(nx, ny + 1) || dfs(nx - 1, ny) || dfs(nx, ny - 1));
	return a;
	return false;
}
int main()
{
	while (1)
	{
		cin >> w >> h;
		if (!w && !h) break;
		else
		{
			cin >> sx >> sy >> gx >> gy >> n;
			sx--; sy--; gx--; gy--;
			loop(i, n)
			{
				int c, d, x, y;
				cin >> c >> d >> x >> y;
				x--; y--;
				input(c, d, x, y);
			}
			/*loop(i, h)
			{
			loop(j, w)
			{
			cout << grid[i][j] << " ";
			}
			cout << endl;
			}*/
			grid = vector<vector<int> >(105, vector<int>(105, 0));
			grid_visited = vector <vector<bool > > (105, vector<bool>(105, false));
			a = false;

			cout << (dfs(sx, sy) ? "OK" : "NG") << endl;
		}
	}

}

C++: #include<iostream>
#include<queue>
#define dr direction
#define cl color
#define fi first
#define se second

using namespace std;
typedef pair<int, int> pii;

class Block{
public:
    int color;// 1~5
    int direction;// 0:-, 1:|
    int x, y;
    void init(int c, int d, int xx, int yy);
};

void Block::init(int c, int d, int xx, int yy){
    color=c;
    direction=d;
    x=xx;
    y=yy;
}

int w, h, xs, ys, xg, yg, n;
int fld[100][100], dis[100][100];
const pii dxdy[]={{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
const int inf=1e8;

string solve(){// bfs
    queue<pii> qu;
    qu.push(make_pair(ys, xs));
    int C=fld[ys][xs];
    fill(dis[0], dis[100], inf);
    dis[ys][xs]=0;

    if(C==0) return "NG";
    while(!qu.empty()){
        pii now=qu.front(); qu.pop();
        if(now.fi==yg&&now.se==xg){
            return "OK";
        }

        for(int k=0; k<4; k++){
            pii nx=make_pair(now.fi+dxdy[k].fi, now.se+dxdy[k].se);
            if(!(0<=nx.fi&&nx.fi<h&&0<=nx.se&&nx.se<w)) continue;
            if(fld[nx.fi][nx.se]!=C) continue;
            if(dis[nx.fi][nx.se]!=inf) continue;

            dis[nx.fi][nx.se]=dis[now.fi][now.se]+1;
            qu.push(nx);
        }
    }

    return "NG";
}

int main(){

    while(1){
        cin>> w>> h;
        if(w==0&&h==0) break;
        cin>> xs>> ys>> xg>> yg>> n;
        xs--; ys--; xg--; yg--;
        Block block[n];
        for(int i=0; i<n; i++){
            int c, d, xx, yy;
            cin>> c>> d>> xx>> yy;
            xx--; yy--;
            block[i].init(c, d, xx, yy);
        }

        // make field
        fill(fld[0], fld[100], 0);
        for(int k=0; k<n; k++){
            int X=block[k].x, Y=block[k].y;
            if(block[k].dr==0){
                for(int i=0; i<2; i++){
                    for(int j=0; j<4; j++){
                        fld[Y+i][X+j]=block[k].cl;
                    }
                }
            }else{
                for(int i=0; i<4; i++){
                    for(int j=0; j<2; j++){
                        fld[Y+i][X+j]=block[k].cl;
                    }
                }
            }
        }
/*
        for(int i=0; i<w; i++){
            for(int j=0; j<h; j++){
                cout<< fld[i][j]<<" ";
            }
            cout<< endl;
        }
//*/
        cout<< solve()<< endl;
    }

    return 0;
}

C++: #include <iostream>
using namespace std;
 
int C[102][102];
int ans;
int xg,yg;
 
void meiro(int W,int H,int c){
  if(W==xg && H==yg){
    ans = 1;
    return;
  }
 
  if(C[W][H]!=c){
    return;
  }
 
  C[W][H] = 0;
 
  meiro(W-1,H  ,c);
  meiro(W  ,H+1,c);
  meiro(W+1,H  ,c);
  meiro(W  ,H-1,c);
}
 
int main(){
  while(1){
    for(int i=0;i<102;i++){
      for(int j=0;j<102;j++){
        C[i][j] = 0;
      }
    }
     
    int w,h;
    cin >> w >> h;
 
    if(w==0 && h==0){
      break;
    }
 
    int xs,ys;
    cin >> xs >> ys;
 
    cin >> xg >> yg;
 
    int n;
    cin >> n;
    int c[102],d[102],x[102],y[102];
 
    int cbase;
 
    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];
 
      if(d[i]==0){
        for(int j=x[i];j<x[i]+4;j++){
          for(int k=y[i];k<y[i]+2;k++){
            C[j][k]=c[i];
          }
        }
      }
      if(d[i]==1){
        for(int j=x[i];j<x[i]+2;j++){
          for(int k=y[i];k<y[i]+4;k++){
            C[j][k]=c[i];
          }
        }
      }
    }
    ans = 0;
 if(C[xs][ys] == 0){
      cout << "NG" << endl;
      continue;
    }
    meiro(xs,ys,C[xs][ys]);
   
    if(ans==1){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }
 
  return 0;
}