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 <vector>

using namespace std;

int dxdy[4][2] = { {0, 1}, {0, -1}, {1, 0}, {-1, 0}  };

bool doFill(vector<vector<char> >& brd, int i, int j, int w, int h, char c){
    if( i < 0 || j < 0 || i >= h || j >= w ) return false;
    if(brd[i][j] == 'G') return true;
    else if(brd[i][j] == c) brd[i][j] = '*';
    else return false;
    bool b = false;
    for(int k = 0; k < 4; ++k){
       b |= doFill(brd, i+dxdy[k][0], j+dxdy[k][1], w, h, c);
    }
    return b;
}

int main(){
    int w,h;
    int sx, sy;
    int gx, gy;
    int n;
    int i,j;
    cin >> w >> h;
    if(!w && !h) return 0;
    cin >> sx >> sy;
    cin >> gx >> gy;
    cin >> n;
    sx--; sy--; gx--; gy--;
    vector< vector<char> > board(h,vector<char>(w));
    for(i=0;i<h;++i)
        for(j=0;j<w;++j) board[i][j] = '.';
    while(n--){
        char c;
        int d, x, y;
        cin >> c >> d >> x >> y;
        x--; y--;
        for(i=0;i<2;++i){
            for(j=0;j<4;++j) {
                if(d == 1) 
                    board[y+j][x+i] = c;
                else
                    board[y+i][x+j] = c;
            }
        }
    }
    board[gy][gx] = 'G';
    if(doFill(board, sy, sx, w, h, board[sy][sx])){
        cout << "OK" << endl;
    } else {
        cout << "NG" << endl;
    }/*
    for(i=0;i<h;++i) {
        for(j=0;j<w;++j) cout << board[i][j];
        cout << endl;
    }
    cout << endl;
    */return main();
}

C++: #include <iostream>
#include <cstdio>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<(n);i++)
int dy[] = {1, 0, 0, -1};
int dx[] = {0, 1, -1, 0};
int b[110][110];
int w, h;
int xs, ys, xg, yg;
int color;
bool flag = false;
bool used[110][110];

void dfs(int y, int x){
	rep(i, 4){
		int ny = y + dy[i], nx = x + dx[i];
		if(used[ny][nx]) continue;//???????????¨???????????????????????????
		if(!(0 <= ny && ny < h && 0 <= nx && nx < w)) continue;
		if(b[ny][nx] != color) continue;
		if(ny == yg && nx == xg){
			used[ny][nx] = true;
			flag = true; return;//????????????
		}
		used[ny][nx] = true;
		dfs(ny, nx);
	}
	return;//????????¢?????¨???????????????
}

int main(void){
	while(1){
		rep(i, 110)rep(j, 110){
			b[i][j] = -1; used[i][j] = false;
		}
		cin >> w >> h;
		if(w == 0 && h == 0) return 0;
		cin >> xs >> ys >> xg >> yg;
		xs--; ys--; xg--; yg--;
		int n; cin >> n;
		rep(i, n){
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			x--; y--;
			if(d == 0){//?¨?
				b[y][x] = b[y][x + 1] = b[y][x + 2] = b[y][x + 3] = c;
				b[y + 1][x] = b[y + 1][x + 1] = b[y + 1][x + 2] = b[y + 1][x + 3] = c;
			}else{//???
				b[y][x] = b[y][x + 1] = c;
				b[y + 1][x] = b[y + 1][x + 1] = c;
				b[y + 2][x] = b[y + 2][x + 1] = c;
				b[y + 3][x] = b[y + 3][x + 1] = c;
			}
		}
		color = b[ys][xs];
		if(color == -1) {//?????????????????????????????????
			printf("NG\n"); continue;
		}
		used[ys][xs] = true; flag = false;
		dfs(ys, xs);
		if(flag) printf("OK\n");
		else printf("NG\n");
	}
}

C++: #include<iostream>
#include<cmath>
#include<cstring>
using namespace std;
bool used[101][101];
int mas[101][101],sx,sy,gx,gy,w,h;
int d[]={0,1,0,-1};
int dfs(int,int,int);
int main(){
  int n,c,d,x,y,tate,yoko;
  while(cin >> w >> h && w||h){
    memset(used,false,sizeof(used));
    memset(mas,-1,sizeof(mas));
    cin >> sy >> sx >> gy >> gx >> n;
    sy--,sx--,gx--,gy--;
    while(n--){
      cin >> c >> d >> y >> x;
      x--,y--;
      d==0 ? (tate=2,yoko=4) : (tate=4,yoko=2);
      for(int i=x;i<x+tate;i++){
	for(int j=y;j<y+yoko;j++){
	  mas[i][j] = c;
	}
      }
    }
    dfs(sx,sy,mas[sx][sy]);
    cout << (used[gx][gy]?"OK":"NG") << endl;
  }
}
int dfs(int x,int y,int color){
  used[x][y] = true;
  for(int i=0;i<4;i++){
    int nx=x+d[i],ny=y+d[3-i];
    if(x>=0&&x<h&&y>=0&&y<w&&mas[nx][ny]==color&&used[nx][ny]==false){
	dfs(nx,ny,color);
      }
  }
}

C++: #include <iostream>

using namespace std;

int w, h;
int xg, yg, xs, ys;
int data[102][102];
int dx[]={1, 0, -1, 0};
int dy[]={0, -1, 0, 1};
bool dfs(int, int, int);

main(){
  int c, d, x, y;
  while(1){
    cin >> w >> h;
    if(w==0 && h==0) break;
    int n;
    cin >> xs >> ys >> xg >> yg >> n;
    for(int i=0;i<h+2;i++){
      for(int j=0;j<w+2;j++){
	data[i][j]=0;
      }
    }
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
      int tw, th;
      if(d==0){
	tw=4;
	th=2;
      }else{
	tw=2;
	th=4;
      }
      for(int i=0;i<=th-1;i++){
	for(int j=0;j<=tw-1;j++){
	  data[y+i][x+j]=c;
	}
      }
    }
    if(dfs(ys, xs, data[ys][xs])) cout << "OK" << endl;
    else cout << "NG" << endl;
  }
  return 0;
}

bool dfs(int y, int x, int c){
  if(c==0 || data[y][x]!=c) return false;
  if(y==yg && x==xg) return true;
  data[y][x]=0;
  for(int i=0;i<4;i++){
    if(dfs(y+dy[i], x+dx[i], c)) return true;
  }
  return false;
}