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 <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
using namespace std;
inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string toStr(T x) { ostringstream sout; sout << x; return sout.str();}
typedef vector<int> vi;
typedef vector<vi>  vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define REP(i,n) FOR(i,0,(n)-1)
const double EPS = 1e-12;
const double PI = acos(-1.0);
const int INF = INT_MAX/10;

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

int main() {
	int w, h;
	while(cin >> w >> h, w) {
		vvi field(h, vi(w));
		vvi visit(h, vi(w));
		
		int xs, ys, xg, yg, n;
		cin >> xs >> ys >> xg >> yg >> n;

		int c, d, x, y;
		REP(i, n) {
			cin >> c >> d >> x >> y;
			REP(j, 4) {
				REP(k, 2) {
					if(d) {
						field[y+j][x+k] = c;
					} else {
						field[y+k][x+j] = c;
					}
				}
			}
		}

		stack<pii> S;
		S.push(make_pair(xs, ys));
		bool goal = false;
		while(!S.empty()) {
			pii p = S.top();
			S.pop();

			if(p.first == xg && p.second == yg) {
				goal = true;
				break;
			}

			int nx, ny;
			REP(d, 4) {
				nx = p.first + dx[d];
				ny = p.second + dy[d];
				if(0<=nx && nx<w && 0<=ny && ny < h) {
					if(!visit[ny][nx] && field[ny][nx] == field[ys][xs]) {
						visit[ny][nx] = 1;
						S.push(make_pair(nx, ny));
					}
				}

			}
		}

		if(goal) {
			cout << "OK" << endl;
		} else {
			cout << "NG" << endl;
		}
	}
}

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

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

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

bool input() {
  cin >> w >> h;
  if (!w && !h) {
    return false;
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      b[i][j] = -1;
    }
  }
  cin >> xs >> ys;
  cin >> xg >> yg;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    int c, d, x, y;
    cin >> c >> d >> x >> y;
    if (!d) {
      for (int i = 0; i < 2; ++i) {
        for (int j = 0; j < 4; ++j) {
          b[y + i][x + j] = c;
        }
      }
    } else {
      for (int i = 0; i < 4; ++i) {
        for (int j = 0; j < 2; ++j) {
          b[y + i][x + j] = c;
        }
      }
    }
  }
  return true;
}

void dfs(int c, int y, int x) {
  if (b[y][x] != c) {
    return;
  }
  b[y][x] = -1;
  for (int i = 0; i < 4; ++i) {
    dfs(c, y + dy[i], x + dx[i]);
  }
}

void solve() {
  if (b[ys][xs] != b[yg][xg]) {
    cout << "NG" << endl;
    return;
  }

  dfs(b[ys][xs], ys, xs);
  if (b[yg][xg] == -1) {
    cout << "OK" << endl;
  } else {
    cout << "NG" << endl;
  }
}

int main() {
  while (input()) {
    solve();
  }
  return 0;
}

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



typedef vector<vector<int> > Matrix;
int w,h,xs,ys,xg,yg,n;
string res = "NG";

class Block{
public:
  int color;
  int direction;
  int x,y,dx,dy;
  void write(Matrix &board){
    if(direction == 0)
      dx = 4,dy = 2;
    else if(direction == 1)
      dx = 2,dy = 4;
    for(int i=0; i<dx; ++i){
      for(int j=0; j<dy; ++j){
	(board.at(x+i)).at(y+j) = color;
      }
    }
  }
};
  
void func(Matrix &board,int nx,int ny){
  if(board[nx][ny] == 0){
    res = "NG";
    return;
  }
  if( nx==xg && ny==yg){
    res = "OK";
    return;
  }
  int temp = board[nx][ny];
  board[nx][ny] = 0;
  if( 0<=nx-1 && temp==board[nx-1][ny])
    func(board,nx-1,ny);
  if( 0<=ny-1 && temp==board[nx][ny-1])
    func(board,nx,ny-1);
  if( nx+1<=w && temp==board[nx+1][ny])
    func(board,nx+1,ny);
  if( ny+1<=h && temp==board[nx][ny+1])
    func(board,nx,ny+1);
}


int main(void){

  while(1){
    cin >> w >> h;
    if( w==0 && h==0) return 0;
    cin >> xs >> ys >> xg >> yg >> n;
    xs--; ys--; xg--; yg--;
    Block *object[n];
    Matrix board(w, vector<int>(h,0));
    for(int i=0; i<n; ++i){
      object[i] = new Block();
      cin >> object[i]->color;
      cin >> object[i]->direction;
      cin >> object[i]->x;
      cin >> object[i]->y;
      --object[i]->x; --object[i]->y;
      object[i]->write(board);	    
    }
    func(board,xs,ys);
    cout << res << endl;
    delete[] *object;
    board.clear();
  }
  return 0;
}