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 <cstdio>
#include <cstring>

using namespace std;


// 0								1
// (0, 0) (1, 0) (2, 0) (3, 0)		(0, 0) (1, 0)
// (0, 1) (1, 1) (2, 1) (3, 1)		(0, 1) (1, 1)
//									(0, 2) (1, 2)
//									(0, 3) (1, 3)
const int dy[2][8] = {{0,0,0,0,1,1,1,1},{0,0,1,1,2,2,3,3}}, dx[2][8] = {{0,1,2,3,0,1,2,3},{0,1,0,1,0,1,0,1}};
const int ddy[4] = {-1,0,1,0}, ddx[4] = {0,1,0,-1};
int table[100][100];

void dfs(int x,int y,int w,int h){
	int now = table[y][x];
	table[y][x] = 0;
	for(int i = 0;i < 4;i++){
		if(x + ddx[i] >= 0 && x + ddx[i] < w && y + ddy[i] >= 0 && y + ddy[i] < h && table[y + ddy[i]][x + ddx[i]] != 0 && now == table[y + ddy[i]][x + ddx[i]]){
			dfs(x + ddx[i],y + ddy[i],w, h);
		}
	}
}


int main(void){
	int sx, sy, gx, gy, n, c, d, x, y, i, j, w, h;
	char ans[3];
	while(1){
		scanf("%d%d",&w,&h);
		if(w == 0 && h == 0){
			break;
		}
		strcpy(ans,"NG");
		scanf("%d%d%d%d%d",&sx,&sy,&gx,&gy,&n);
		sx--; sy--; gx--; gy--;
		memset(table,0,sizeof(table));
		for(i = 0;i < n;i++){
			scanf("%d%d%d%d",&c,&d,&x,&y);
			for(j = 0;j < 8;j++){
				table[y + dy[d][j] - 1][x + dx[d][j] - 1] = c;
			}
		}
/*		for(i = 0;i < h;i++){
			for(j = 0;j < w;j++){
				printf("%d ",table[i][j]);
			}
			printf("\n");
		}*/
		if(table[gy][gx] != 0){
			dfs(sx, sy, w, h);
			if(table[gy][gx] == 0){
				strcpy(ans,"OK");
			}
		}
		printf("%s\n",ans);
	}
	return 0;
}

C++: #include<iostream>
using namespace std;
#define MAX 100
#define BLANK 0
#define LONG 4
#define SHORT 2
#define HORIZONTAL 0
#define VERTICAL 1
#define VISITED 9

int field[MAX+2][MAX+2];
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
void rec(int x,int y,int c)
{
  int i;
  if(field[x][y]!=c)return;
  field[x][y]=VISITED;
  for(i=0;i<4;i++)rec(x+dx[i],y+dy[i],c);
  return;
}

int main()
{
  int w,h,xs,ys,xg,yg,n,c,d,x,y;
  int i,j;
  while(cin>>w>>h>>xs>>ys>>xg>>yg>>n,w|h){
    for(j=1-1;j<=h+1;j++)for(i=1-1;i<=w+1;i++)field[i][j]=BLANK;
    while(n-->0){
      cin>>c>>d>>x>>y;
      if(d==HORIZONTAL)
	for(i=0;i<LONG;i++)for(j=0;j<SHORT;j++)field[x+i][y+j]=c;
      else
	for(i=0;i<SHORT;i++)for(j=0;j<LONG;j++)field[x+i][y+j]=c;
    }
    if(field[xs][ys]!=BLANK)rec(xs,ys,field[xs][ys]);
    puts(field[xg][yg]==VISITED?"OK":"NG");
  }
}

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


#define rep(i,n) for(short i = 0; i < n; i++)
#define MAX 50

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

typedef pair<short,short> P;
P S,G;
short w,h;

short color;
	queue<P> que;
	
bool check(short maze[MAX][MAX])
{
	que.push(S);

	color = maze[S.second][S.first];
	if(color < 0)
		return false;

	short nx,ny;
	while(que.size()){
		P p = que.front();	que.pop();

		if(p == G){
			while(que.size())
				que.pop();
			return true;
		}

		rep(i,4){
			nx = p.first + dx[i], ny = p.second + dy[i];
			
			if(nx > -1 && ny > -1 && nx < w && ny < h &&
				maze[ny][nx] == color){
					maze[ny][nx] = -1;
					que.push(P(nx,ny));
			}

		}
	}


	
	return false;
}

int main(void)
{
	short n,c,d,x,y;
	short maze[MAX][MAX];
	while(cin >> w >> h, w){
	/*	rep(i,MAX){
			rep(j,MAX)
				maze[i][j] = -10;
		}*/
		cin >> S.first >> S.second;
		cin >> G.first >> G.second;
		S.first = S.first / 2;
		S.second= S.second/ 2;

		cin >> n;

		rep(i,n){
			cin >> c >> d >> x >> y;
			x /= 2;
			y /= 2;
			x++;
			y++;

			if(d == 0)
				maze[y][x] = maze[y][x+1] = c;
			else
				maze[y][x] = maze[y+1][x] = c;
		}
		
		if(/*maze[S.second][S.first] > 0 && */maze[S.second][S.first] == maze[G.second][G.first] && check(maze))
			cout << "OK\n";
		else
			cout << "NG\n";

	}
	
	return 0;
}

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

int xx[4] = {0, 1, 0, -1};
int yy[4] = {1, 0, -1, 0};
int block[100][100];
bool already[100][100];
int w, h;
int xs, ys;
int xg, yg;
bool dfs(int nex, int ney);

int main(){
  int n;
  
  while(1){
    memset(block, 0, sizeof(block));
    memset(already, 0, sizeof(already));
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    cin >> xs >> ys;
    cin >> xg >> yg;
    cin >> n;
    for(int i = 0; i < n; i++){
      int c, d, x, y;
      int wide, high;
      cin >> c >> d >> x >> y;
      if(d){
	wide = 2; high = 4;
      }
      else{
	wide = 4; high = 2;
      }
      for(int j = 0; j < high; j++){
	for(int k = 0; k < wide; k++){
	  block[y+j][x+k] = c;
	}
      }
    }
    bool ans = false;
    if(block[ys][xs] == block[yg][xg]){
      ans = dfs(xs, ys);
      if(ans) cout << "OK" << endl;
      else cout << "NG" << endl;
    }
    else cout << "NG" << endl;
  }
}

bool dfs(int nex, int ney){
  already[nex][ney] = true;
  if(nex == xg && ney == yg) return true;
  for(int i = 0; i < 4; i++){
    int nx = nex + xx[i];
    int ny = ney + yy[i];
    if(0 <= nx && 0 <= ny && ny < h && nx < w && !already[ny][nx] && block[ys][xs] == block[ny][nx]) return dfs(nx, ny);
  }
  return false;
}