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<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<time.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double EPS=1e-10;
const int inf=1e8;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
int sx,sy;
int gx,gy;
vvi tmp;
int q;
int dx[]={0,0,1,-1};
int dy[]={-1,1,0,0};
void solve(int x,int y){
	tmp[x][y]=-1;
	rep(i,4){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(tmp[nx][ny]==q){solve(nx,ny);}
	}
}
int main(){
	int n,m;
	while(cin>>n>>m,n+m){
		vvi in(n+2,vi(m+2));
		cin>>sx>>sy>>gx>>gy;
		cin>>n;
		while(n--){
			int a,b,c,d;
			cin>>a>>b>>c>>d;
			if(!b)rep(i,4)rep(j,2)in[c+i][d+j]=a;
			else rep(i,2)rep(j,4)in[c+i][d+j]=a;
		}
		tmp=in;
		//rep(i,in.size()){rep(j,in[0].size())cout<<in[i][j]<<" ";cout<<endl;}
		if(in[sx][sy]){
			q=in[sx][sy];
			solve(sx,sy);
		}
		//cout<<endl;
		//rep(i,tmp.size()){rep(j,tmp[0].size())cout<<tmp[i][j]<<" ";cout<<endl;}
		cout<<((in[sx][sy]==2&&in[gx][gy]==2&&tmp[gx][gy]==-1)?"OK":"NG")<<endl;
		//rep(i,22){rep(j,22)cout<<tmp[i][j]<<" ";cout<<endl;}
	}
}

C++: #include<bits/stdc++.h>
using namespace std;
int h,w,a[100][100];
int d1[]={0,0,1,-1},d2[]={1,-1,0,0};
void dfs(int y,int x,int c){
  a[y][x]=0;
  for(int i=0;i<4;i++){
    int yy=d2[i]+y,xx=d1[i]+x;
    if(yy>=0&&xx>=0&&xx<w&&yy<h)
      if(a[yy][xx]==c)
        dfs(yy,xx,c);
  }
}
int main(){
  while(cin>>w>>h,h){
    memset(a,0,sizeof(a));
    int sx,sy,gx,gy;
    cin>>sx>>sy>>gx>>gy;
    sx--;sy--;gx--;gy--;
    int m;
    cin>>m;
    while(m--){
      int q,w,e,r;
      cin>>q>>w>>e>>r;
      w;e--;r--;
      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}};
      for(int i=0;i<8;i++)
        a[r+dy[w][i]][e+dx[w][i]]=q;
    }
    if(a[sy][sx]!=0){
      dfs(sy,sx,a[sy][sx]);
      if(a[gy][gx]==0)cout<<"OK"<<endl;
      else goto L;
    }
    else{L:;
      cout<<"NG"<<endl;
    }
  }
}

C++: #include <iostream>

#define rep(i, a, b) for(int i = a; i < b; i ++)

using namespace std;

int w, h, xs, ys, xg, yg, n;
int map[100][100] = {0};
int map2[100][100] = {0};
void exp(int x, int y, int c) {
  if(x <= 0 || w <= x || y <= 0 || h <= y) return;
  if(map[x][y] != c || map2[x][y] == 1) return;

  map2[x][y] = 1;
  exp(x-1, y, c);
  exp(x+1, y, c);
  exp(x, y-1, c);
  exp(x, y+1, c);

  return;
}

int main() {
  while(cin >> w >> h >> xs >> ys >> xg >> yg >> n, w) {
    rep(i, 0, h) {
      rep(j, 0, w) {
	map[j][i] = 0;
	map2[j][i] = 0;
      }
    }

    int block[4];
    int start[4];
    rep(i, 0, n) {
      rep(lp, 0, 4) {
	cin >> block[lp];
      }

      switch(block[1]) {
      case(0):
	rep(lp1, 0, 2) {
	  rep(lp2, 0, 4) {
	    map[block[3]+lp1][block[2]+lp2] = block[0];
	  }
	}
      case(1):
	rep(lp1, 0, 4) {
	  rep(lp2, 0, 2) {
	    map[block[3]+lp1][block[2]+lp2] = block[0];
	  }
	}
      }
    }
    exp(xs, ys, map[xs][ys]);
    cout << ((map2[xg][yg] == 1)?("OK"):("NG")) << endl;
  }    
  return 0;
}

C++: #include <iostream>
#include <cstdio>

using namespace std;

#define reep(i,n,m) for(int i=(n);i<(m);i++)
#define rep(i,n) reep(i,0,n)

bool flg[150][150];
int fld[150][150];
int w,h;
int xg,yg;
bool ans;

void check(int c,int x,int y){
    if(x == xg && y == yg){
        ans = true;
        return;
    }

    if(fld[y][x]!=c){
        return;
    }

    if(flg[y][x]){
        return;
    }
    flg[y][x] = true;

    int dx[] = {0,0,1,-1};
    int dy[] = {1,-1,0,0};
    rep(i,4){
        int nx = x+dx[i];
        int ny = y+dy[i];
        if(nx<0 || nx>=w || ny<0 || ny>=h){
            continue;
        }
        check(c,nx,ny);
    }
}

int main(){
    while(cin >> w >> h,w+h){
        rep(i,150){rep(k,150){flg[i][k]=false;}}
        ans = false;
        int xs,ys;
        cin >> xs >> ys;
        cin >> 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--;
            int width,height;
            if(d == 0){
                width = 4;
                height = 2;
            }else{
                width = 2;
                height = 4;
            }

            reep(ny,y,y+height){
                reep(nx,x,x+width){
                    fld[ny][nx] = c;
                }
            }
        }

        reep(i,1,6){
            check(i,xs,ys);
        }
        if(ans){
            puts("OK");
        }else{
            puts("NG");
        }
    }
}