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 <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define shosu(n) setprecision(n)
using namespace std;
int w, h, xs, ys, xg, yg;
int mp[110][110];

bool dfs(int x, int y, int f) {
  if (x >= w || y >= h || x < 0 || y < 0 || mp[y][x] != f)
    return false;
  if (y == yg && x == xg && mp[y][x] == f)
    return true;
  mp[y][x] = 9;
  return dfs(x + 1, y, f) || dfs(x - 1, y, f) || dfs(x, y + 1, f) ||
         dfs(x, y - 1, f);
}

int main() {
  while (cin >> w >> h) {
    if (w == 0 && h == 0)
      break;
    int n;
    cin >> xs >> ys >> xg >> yg >> n;
    xs--;
    ys--;
    xg--;
    yg--;
    int c, d, x, y;
    rep(i, n) {
      cin >> c >> d >> x >> y;
      if (d == 0) {
        for (int i = y - 1; i < y + 1; i++)
          for (int j = x - 1; j < x + 3; j++) {
            mp[i][j] = c;
          }
      } else {
        for (int i = y - 1; i < y + 3; i++)
          for (int j = x - 1; j < x + 1; j++) {
            mp[i][j] = c;
          }
      }
    }
    cout << (dfs(xs, ys, mp[ys][xs]) ? "OK" : "NG") << endl;
  }
  return 0;
}

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

int b[100][100];
int vis[100][100];

int w, h;
bool in(int x, int y) {
	return 0 <= x && x < w && 0 <= y && y < h;
}


int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	while(cin >> w >> h, w + h) {
		int xs, ys, xg, yg, n;
		cin >> xs >> ys >> xg >> yg >> n;
		xs--, ys--, xg--, yg--;

		memset(b, 0, sizeof b);
		for(int i = 0; i < n; i++) {
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			x--, y--;
			int H = 2, W = 4;
			if(d == 1) swap(H, W);
			for(int dx = 0; dx < W; dx++) {
				for(int dy = 0; dy < H; dy++) {
					b[y + dy][x + dx] = c;
				}
			}
		}

		if(b[ys][xs] == 0 || b[ys][xs] != b[yg][xg]) {
			cout << "NG" << endl;
			return 0;
		}

		typedef pair<int, int> P;
		queue<P> q;
		q.push({ xs, ys });
		memset(vis, 0, sizeof vis);
		vis[ys][xs] = 1;
		while(q.size()) {
			int x = q.front().first, y = q.front().second;
			q.pop();
			int dx[4] = { 1, 0, -1, 0 }, dy[4] = { 0, 1, 0, -1 };
			for(int k = 0; k < 4; k++) {
				int nx = x + dx[k], ny = y + dy[k];
				if(in(nx, ny) && b[y][x] == b[ny][nx] && vis[ny][nx] == 0) {
					vis[ny][nx] = 1;
					q.push({ nx, ny });
				}
			}
		}
		if(vis[yg][xg]) {
			cout << "OK" << endl;
		}
		else {
			cout << "NG" << endl;
		}
	}
}

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

string ans;
int w,h,gx,gy;
int map[110][110];
int dx_[4] = {0,1,0,-1};
int dy_[4] = {1,0,-1,0};
int dx[2][8] = {
	{0,1,2,3,0,1,2,3},
	{0,1,0,1,0,1,0,1}
};
int dy[2][8] = {
	{0,0,0,0,1,1,1,1},
	{0,0,1,1,2,2,3,3},
};
void solve(int x,int y,int color){
	if( ans == "OK" || color == 0 ) return;

	for(int i=0 ; i<4 ; ++i ){
		int mx = x + dx_[i];
		int my = y + dy_[i];
		if( mx<0 || mx>w || my<0 || my>h ) continue;
		
		if( map[my][mx] == color ){
			if( mx == gx && my == gy ){
				ans = "OK";
			}else{
				map[my][mx] = 0;
				solve( mx , my , color );
			}
		}
	}
}

int main(){
	int sx,sy,n;
	
	while( cin >> w >> h , w|h ){
		ans = "NG";
		for(int y=0 ; y<110 ; ++y )
			for(int x=0 ; x<110 ; ++x )
				map[y][x] = 0;

		cin >> sx >> sy >> gx >> gy >> n ;
		for(int i=0 ; i<n ; ++i ){
			int c,d,x,y;
			cin >> c >> d >> x >> y;
			for(int j=0 ; j<8 ; j++){
				int mx = x + dx[d][j];
				int my = y + dy[d][j];
				map[my][mx] = c;
			}
		}
		solve( sx , sy , map[sy][sx] );
		cout << ans << endl;
	}
}

C++: #include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<iostream>
#include<queue>
using namespace std;
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
struct point{
    int x,y;
    point(){}
    point(int a, int b){x = a;y = b;}
};
int main(void){

    int w,h;
    while(cin>>w>>h,w){
        int xs,ys,xg,yg,n;
        cin>>xs>>ys>>xg>>yg>>n;
        int field[100][100] = {{0}};
        for(int i = 0;i < n;i++){
            int c,d,x,y;
            int dw = 4,dh = 2;
            cin>>c>>d>>x>>y;
            if(d)swap(dw,dh);
            for(int di = y;di < dh + y && di < h; di++){
                for(int dj = x;dj < dw + x && dj < w;dj++){
                    field[di][dj] = c;
                }
            }
        }
        int C = field[xs][ys];
        bool vis[100][100] = {{false}};
        queue<point> Q;
        Q.push(point(xs,ys));
        if(field[xg][yg] != C || C == 0)cout<<"NG"<<endl;
        else {
            while(!Q.empty()){
                point P = Q.front();
                Q.pop();
                for(int i = 0;i < 4;i++){
                    point p = point(P.x + dx[i],P.y + dy[i]);
                    if(0 <= p.x && p.x < w && 0 <= p.y && p.y < h){
                        if(!vis[p.x][p.y]&&field[p.x][p.y] == C){

                            vis[p.x][p.y] = true;
                            Q.push(p);
                        }
                    }
                }
            }
        }
        if(vis[xg][yg])cout<<"OK"<<endl;
        else cout<<"NG"<<endl;
/*
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cout<<field[i][j]<<" ";
            }
            cout<<endl;
        }
        cout<<endl<<endl;
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cout<<vis[i][j]<<" ";
            }
            cout<<endl;
        }*/
    }


    return 0;
}