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<cstdio>
#include<cstdlib>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<utility>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>

using namespace std;
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
#define INF 1e+9
#define EPS 1e-9
#define rep(i,j) for(int i = 0; i < (j); i++)
#define reps(i,j,k) for(int i = j; i < (k); i++)
typedef long long ll;
int stage[128][128];
int xg,yg;
int w,h;
bool dfs(int x,int y,int col){
	if(x == xg && y == yg && stage[x][y] == col){
		return true;
	}
	rep(i,4){
		if(stage[x+dx[i]][y+dy[i]] == 0)continue;
		if(col == stage[x+dx[i]][y+dy[i]]){
			return dfs(x + dx[i], y + dy[i], col);
		}
	}
	return false;
}
int main(){
	while(scanf("%d%d",&w,&h),w|h){
		memset(stage,0,sizeof(stage));
		int xs,ys;
		scanf("%d%d",&xs,&ys);
		scanf("%d%d",&xg,&yg);

		int n;
		scanf("%d",&n);

		rep(q,n){
			int c,d,x,y;
			scanf("%d%d%d%d",&c,&d,&x,&y);
			if(d == 0){
				reps(i,x,x+4){
					reps(j,y,y+2){
						stage[j][i] = c;
					}
				}

			}
			else{
				reps(i,x,x+2){
					reps(j,y,y+4){
						stage[j][i] = c;
					}
				}
			}
		}
		(dfs(xs,ys,stage[xs][ys])) ? puts("OK") : puts("NG");
	}
	return 0;
}

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

int f[102][102];

void DFS(int x,int y,int c){
    if(f[x][y]!=c)  return;

    f[x][y]=10;
    DFS(x+1,y,c);
    DFS(x-1,y,c);
    DFS(x,y+1,c);
    DFS(x,y-1,c);
}

void print(int w,int h){
    for(int i=1;i<=w;i++){
        for(int j=1;j<=h;j++){
            cout<<f[i][j]<<' ';
        }
        cout<<endl;
    }
}

int main(){
    int w,h;
    int xs,ys;
    int xg,yg;
    int n;
    while(true){
        cin>>w>>h;
        if(w+h==0)  break;
        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                f[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==0){
                for(int j = 0; j<4; j++){
                    for(int k = 0; k<2; k++){
                        f[x+j][y+k] = c;
                    }
                }
            }else{
                for(int j = 0; j<2; j++){
                    for(int k = 0; k<4; k++){
                        f[x+j][y+k] = c;
                    }
                }
            }
        }
        //print(w,h);
        DFS(xs,ys,f[xs][ys]);
        //print(w,h);
        if(f[xg][yg]==10){
            cout<<"OK"<<endl;
        }else{
            cout<<"NG"<<endl;
        }
    }
    return 0;
}

C++: #include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
bool solve(int x,int y,int c);
int ux[2][8]={{0,1,2,3,0,1,2,3},
	      {0,1,0,1,0,1,0,1}};
int uy[2][8]={{0,0,0,0,1,1,1,1},
	      {0,0,1,1,2,2,3,3}};
int dx[4]={0,1,0,-1};
int dy[4]={-1,0,1,0};
int w,h,n;
int b[105][105];
int xs,ys,xg,yg;
int main(void){
  while(1){
    scanf("%d %d",&w,&h);
    if(!w && !h) break;
    memset(b,0,sizeof(b));
    scanf("%d %d %d %d",&xs,&ys,&xg,&yg);
    scanf("%d",&n);
    int c,d,tx,ty;
    for(int i=0;i<n;i++){
      scanf("%d %d %d %d",&c,&d,&tx,&ty);
      for(int j=0;j<8;j++){
	b[tx+ux[d][j]][ty+uy[d][j]]=c;
      }
    }
    if(b[xs][ys]!=0 && b[xg][yg]!=0 && solve(xs,ys,b[xs][ys])) puts("OK");
    else puts("NG");
  }
}

bool solve(int x,int y,int c){
  printf("%d\n",c);
  if(x==xg && y==yg) return true;
  b[x][y]=0;
  for(int i=0;i<4;i++){
    int nx=x+dx[i];
    int ny=y+dy[i];
    if(0<=nx && nx<w && 0<=ny && ny<h){
      if(b[nx][ny]==c){
	if(solve(nx,ny,c)) return true;
      }
    }
  }
  return false;
}

C++: #include <queue>
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){

	int w,h;
	int xs,ys;
	int xg,yg;
	int n;
	while(cin>>w>>h&&!(w==0&&h==0)){
		int field[101][101];
		for(int i = 0; i < 101; i++)
			fill(field[i],field[i]+101,0);

		cin>>xs>>ys;
		cin>>xg>>yg;
		xs--;ys--;xg--;yg--;
		cin>>n;
		for(int i = 0; i < n; i++){
			int c,d,x,y;
			cin>>c>>d>>x>>y;
			x--;y--;
			if(d==0){
				for(int j = y; j < 2+y; j++){
					for(int k = x; k < x + 4; k++){
						field[j][k]=c;
					}
				}
			}
			else{
				for(int j = y; j < 4+y; j++){
					for(int k = x; k < x + 2; k++){
						field[j][k]=c;
					}
				}
			}
		}
		// bfs
		int c=field[ys][xs];
		//if(c==0){
		//	cout<<"NG"<<endl;
		//	continue;
		//}
		queue<pair<int,int> > *prv=new queue<pair<int,int> >();
		queue<pair<int,int> > *nxt=new queue<pair<int,int> >();

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

		bool passed[101][101];
		for(int i = 0; i < 101; i++)
			fill(passed[i],passed[i]+101,false);

		prv->push(make_pair(xs,ys));

		bool fin=false;
		while(prv->size()){
			while(prv->size()){
				pair<int,int> p = prv->front();
				prv->pop();
				if(p.first==yg&&p.second==xg){
					fin=true;
					break;
				}

				if(passed[p.first][p.second])
					continue;
				passed[p.first][p.second]=true;
				for(int i = 0; i < 4; i++){
					int ny=p.first+dy[i];
					int nx=p.second+dx[i];
					if(ny>=0&&nx>=0&&ny<h&&nx<w&&field[ny][nx]==c&&!passed[ny][nx]){
						nxt->push(make_pair(ny,nx));
					}
				}
			}
			if(fin)
				break;
			swap(prv,nxt);
		}
		if(fin){
			cout<<"OK"<<endl;
		}
		else
			cout<<"NG"<<endl;
		delete prv,nxt;
	}

	return 0;
}