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<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;
        }*/
        //cout<<C<<"---"<<field[xg][yg]<<endl;
    }


    return 0;
}

C++: #include <bits/stdc++.h>

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep2(i, n) for(int i = 1; i <= n; ++i)
#define INF 0
#define MAX 102

using namespace std;

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
 
int field[101][101];
int h, w, sx, sy, gx, gy, n;
int col, dire, x, y;
int scol;

bool dfs(int nx, int ny) {
	if(nx == gx && ny == gy) return true;
	field[nx][ny] = -1;
	for(int i = 0; i < 4; ++i) {
		int nex = nx + dx[i];
		int ney = ny + dy[i];
		if(0 < nex && nex <= w && 0 < ney && ney <= h && scol == field[nex][ney]) {
			if(dfs(nex, ney)) return true;
		}
	}
	return false;
}

int main() {
	while(1) {
		scol = INF;
		cin >> h >> w;
		for(int i = 0; i <= h+1; ++i) {
			for(int j = 0; j <= w+1; ++j) {
				field[i][j] = 0;
			}
		}
		if(h == 0 && w == 0) break;
		cin >> sx >> sy >> gx >> gy;
		cin >> n;
		rep(k, n) {
			cin >> col >> dire >> x >> y;
			if(dire == 1) {
				for(int i = 0; i < 4; ++i) {
					for(int j = 0; j < 2; ++j) field[x+j][y+i] = col;
				}
			}
			else {
				for(int i = 0; i < 2; ++i) {
					for(int j = 0; j < 4; ++j) field[x+j][y+i] = col;
				}
			}
		}
		scol = field[sx][sy];
		if(dfs(sx, sy)) cout << "OK" << endl;
		else cout << "NG" << 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(C[W][H]!=c){
    return;
  }

  C[W][H] = -1;

  meiro(W-1,H  ,c);
  meiro(W  ,H+1,c);
  meiro(W+1,H  ,c);
  meiro(W  ,H-1,c);
}

int main(){
  while(1){
    int w,h;
    cin >> w >> h;

    for(int i=0;i<w;i++){
      for(int j=0;j<h;j++){
        C[i][j] = 0;
      }
    }

    if(w==0 && h==0){
      break;
    }

    int xs,ys;
    cin >> xs >> ys;

    cin >> xg >> yg;

    int n;
    cin >> n;
    int c,d,x,y;

    int cbase;

    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;

      if(x == xs &&y == ys){
        cbase = c;
      }

      if(d == 0 && c == cbase){
        for(int j=x;j<x+4;j++){
          for(int k=y;k<y+2;k++){
            C[j][k]=c;
          }
        }
      }
      if(d==1 && c==cbase){
        for(int j = x;j<x+2;j++){
          for(int k=y;k<y+4;k++){
            C[j][k]=c;
          }
        }
      }
    }
    meiro(xs,ys,cbase);

    if(C[xg][yg] == -1){
      cout << "OK" << endl;
    }
    if(C[xg][yg] != -1 || C[xs][ys] == 0){
      cout << "NG" << 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(C[W][H]!=c){
    return;
  }

  C[W][H] = '.';

  meiro(W-1,H  ,c);
  meiro(W  ,H+1,c);
  meiro(W+1,H  ,c);
  meiro(W  ,H-1,c);
}

int main(){
  while(1){
    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[n],d[n],x[n],y[n];

    for(int i=0;i<102;i++){
      for(int j=0;j<102;j++){
        C[w][h] = 0;
      }
    }
    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;
    meiro(xs,ys,C[xs][ys]);

    if(C[xg][yg]){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }

  return 0;
}