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];
bool mem[128][128];
int xg,yg;
int w,h;
void dfs(int x,int y,int col){
	if(x < 1 || y < 1 || x > w || y > h)return ;
	if(mem[x][y])return ;
	if(stage[x][y] != col)return ;
	mem[x][y] = true;
	rep(i,4)if(col == stage[x+dx[i]][y+dy[i]])dfs(x + dx[i], y + dy[i], col);
	return ;
}
int main(){
	while(scanf("%d%d",&w,&h),w|h){
		memset(stage,0,sizeof(stage));
		rep(i,128)rep(j,128)mem[i][j] = false;
		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]);
		bool f = mem[xg][yg];
		(f) ? puts("OK") : puts("NG");
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
bool b;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};

void dfs(int a[][110] ,int x , int y , int w , int h , int xg , int yg , int c){
	if(x==xg&&y==yg) {b=true;return;}
	for(int i=0;i<4;++i){
		int tx=x+dx[i];
		int ty=y+dy[i];
		if(tx<=0||ty<=0||tx>w||ty>h) continue;
		if( a[tx][ty]!=c || a[tx][ty]==0) continue;
		if(b) continue;
		dfs( a,tx,ty,w,h,xg,yg,c);
	}
}
int main(){
	int w , h;
	while(cin >> w >> h , w||h){
		int xs , ys , xg , yg ;
		int n;
		b=false;
		int board[110][110]={0};
		cin >> xs >> ys >> xg >> yg >> n;
		for(int i=0;i<n;++i){
			int c , d , x , y;
			cin >> c >> d >> x >> y;
			if(!d){
				for(int k=y;k<y+2;++k){
					for(int j=x;j<x+4;++j){
						board[j][k]=c;
					}
				}
			} else {
				for(int k=y;k<y+4;++k){
					for(int j=x;j<x+2;++j){
						board[j][k]=c;
					}
				}
			}
		}
		int sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {
		}
		else dfs(board , xs , ys , w , h , xg , yg , sc);
		cout << ( b ? "OK" : "NG") << endl;
	}
	return 0;
}

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

int F[102][102];

bool DFS(int X, int Y, int Xg, int Yg, int c){
	if(F[Y][X] != c){
		return false;
	}else if(F[Y][X] == c && X == Xg && Y == Yg){
		return true;
	}
	F[Y][X] = -1;
	if(DFS(X, Y - 1, Xg, Yg, c)){
		return true;
	}else if(DFS(X + 1, Y, Xg, Yg, c)){
		return true;
	}else if(DFS(X, Y + 1, Xg, Yg, c)){
		return true;
	}else if(DFS(X - 1, Y, Xg, Yg, c)){
		return true;
	}
	
	return false;
}

int main(){

while(true){
	int w, h;
	cin >> w >> h;
	if(w == 0 && h == 0){
		break;
	}
	int xs, ys, xg, yg;
	cin >> xs >> ys >> xg >> yg;
	int n;
	cin >> n;
	
	for(int i = 0; i < n; i++){
		int c, d, x, y;
		cin >> c >> d >> x >> y;
		if(d == 0){
			for(int X = x; X < x + 4; X++){
				for(int Y = y; Y < y + 2; Y++){
					F[Y][X] = c;
				}
			}
		}else if(d == 1){
			for(int X = x; X < x + 2; X++){
				for(int Y = y; Y < y + 4; Y++){
					F[Y][X] = c;
				}
			}
		}
	}
	if(DFS(xs, ys, xg, yg, F[xg][yg])){
		cout << "OK" << "\n";
	}else{
		cout << "NG" << "\n";
	}
}
	return 0;
}

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

int F[102][102];
int xg,yg;
int flag = 0;

void DFS(int Y,int X,int c){
  if(F[Y][X]!=c){
    return;
  }
  if(Y == xg && X == yg){
    flag = 1;
  }

  F[Y][X] = 0;
  DFS(Y-1,X  ,c);
  //DFS(Y-1,X+1,c);
  DFS(Y  ,X+1,c);
  //DFS(Y+1,X+1,c);
  DFS(Y+1,X  ,c);
  //DFS(Y+1,X-1,c);
  DFS(Y  ,X-1,c);
  //DFS(Y-1,X-1,c);
}


int main(){
  int w,h,xs,ys,n;
  while(1){
  cin >> w >> h;
  if(w == 0 && h == 0)
    break;
  cin >> xs >> ys >> xg >> yg >> 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++){
        F[x+j][y] = c;
        F[x+j][y+1] = c;
      }
    } else {
      for(int j=0;j<4;j++){
        F[x][y+j] = c;
        F[x+1][y+j] = c;
      }
    }
  }

  DFS(xs,ys,F[xs][ys]);
  if(flag == 1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
}
}

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

int F[102][102];

void DFS(int Y,int X,int C){
   if(F[Y][X]!=C)
      return;
   F[Y][X]=6;
   DFS(Y-1,X,C);
   DFS(Y,X+1,C);
   DFS(Y+1,X,C);
   DFS(Y,X-1,C);
} 

int main(){
   int w,h,xs,ys,xg,yg,n;
   int c,d,x,y;
   while(true){
      cin >> w >> h;
      if(w==0&&h==0)
         break;
      cin >> xs >> ys;
      cin >> xg >> yg;
      cin >> n;
      for(int i=1;i<=n;i++){
         cin >> c >> d >> x >> y;
         if(d==0){
             F[y+1][x+1]=c;
             F[y+1][x+2]=c;
             F[y+1][x+3]=c;
             F[y+1][x+4]=c;  
             F[y+2][x+1]=c;
             F[y+2][x+2]=c;
             F[y+2][x+3]=c;
             F[y+2][x+4]=c;   
         }
         else{
             F[y+1][x+1]=c;
             F[y+2][x+1]=c;
             F[y+3][x+1]=c;
             F[y+4][x+1]=c;  
             F[y+1][x+2]=c;
             F[y+2][x+2]=c;
             F[y+3][x+2]=c;
             F[y+4][x+2]=c;   
         }
      }
      if(F[ys+1][xs+1]!=1&&F[ys+1][xs+1]!=2&&F[ys+1][xs+1]!=3&&F[ys+1][xs+1]!=4&&F[ys+1][xs+1]!=5)
         cout << "NG" << endl;
      else
         DFS(ys+1,xs+1,F[ys][xs]);
      if(F[yg+1][xg+1]==F[ys+1][xs+1])
         cout << "OK" << endl;
      else
         cout << "NG" << endl;
      for(int i=1;i<=w;i++)
         for(int j=1;j<=h;j++)
            F[i][j]=0;
      
   }
   return 0;
}