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<stack>
#include<string.h>
using namespace std;
struct ST {
	int a;
	int b;
	int c;
};
long long brock[1000][1000];
long long ds[1000][1000];
int q[4]={0,-1,0,1};
int p[4]={1,0,-1,0};
int main(){
	stack <ST> S;
	ST ma;
	ST ba;
	int w,h;//???????????§??????
	int xs,ys;//??????????????§?¨?
	int xg,yg;//??´????????§?¨?
	int n;//????????????????????°
	int c,d,x,y;//????????????????????±
	int i,j,m,check=0;
	while(1){
		memset(ds,0,sizeof(ds));
		memset(brock,0,sizeof(brock));
		cin>>w>>h;//???????????§????????\???
		if(w==0&&h==0){
			break;
		}
		cin>>xs>>ys>>xg>>yg;//??????????????¨??´???????????§?¨???\???
		cin>>n;//????????????????????°
		for(i=0;i<n;i++){
			cin>>c>>d>>x>>y;
			if(d==0){
				for(m=y;m<y+2;m++){
					for(j=x;j<x+4;j++){
						brock[m][j]=c;
					}
				}
			}
			else{
				for(m=y;m<y+4;m++){
					for(j=x;j<x+2;j++){
						brock[m][j]=c;
					}
				}
			}
		}
		/*for(i=1;i<h;i++){
			for(j=1;j<w;j++){
				cout<<brock[i][j];
			}
			cout<<endl;
		}*/
		if(brock[ys][xs]!=brock[yg][xg]){
			cout<<"NG"<<endl;
		}
		else{
			ma.a=ys;
			ma.b=xs;
			ma.c=brock[ys][xs];
			ds[ys][xs]=1;
			S.push(ma);
			check=0;
			while(!S.empty()){
				ba=S.top();
				S.pop();
				ds[ba.a][ba.b]=1;
				if(ba.a==yg&&ba.b==xg){
					check=1;
					break;
				}
				if(ba.c==brock[yg][xg]){
					for(i=0;i<4;i++){
						if(ba.a+p[i]>0&&ba.a+p[i]<=h&&ba.b+q[i]>0&&ba.b+q[i]<=w&&ds[ba.a+p[i]][ba.b+q[i]]==0){
							ma.a=ba.a+p[i];
							ma.b=ba.b+q[i];
							ma.c=brock[ba.a+p[i]][ba.b+q[i]];
							S.push(ma);
						}
					}
				}
			}
			if(check==1){
				cout<<"OK"<<endl;
			}
			else{
				cout<<"NG"<<endl;
			}
		}
	}
	return 0;
}

C++: #include<stdio.h>
int w,h;
int xs,ys;
int xg,yg;
int n;
int ib[100][100];
bool used[100][100];
int i,j;
int dx[4]={-1,0,0,1};
int dy[4]={0,1,-1,0};

bool search(int a,int b,int c){
	bool ok=false;
	for(int k=0;k<4;k++){
		if(a+dx[k]>=0&&a+dx[k]<w&&b+dy[k]>=0&&b+dy[k]<h){
			if(!used[a+dx[k]][b+dy[k]]&&ib[a+dx[k]][b+dy[k]]==c){
				used[a+dx[k]][b+dy[k]]=true;
				if(a+dx[k]==xg-1&&b+dy[k]==yg-1)return true;
				if(search(a+dx[k],b+dy[k],c))ok=true;
			}
		}
	}
	return ok;
}

int main(){
	while(1){
		scanf("%d %d",&w,&h);
		if(w==0&&h==0)return 0;
		scanf("%d %d",&xs,&ys);
		scanf("%d %d",&xg,&yg);
		scanf("%d",&n);
		for(i=0;i<w;i++)for(j=0;j<h;j++){
			ib[i][j]=0;
			used[i][j]=false;
		}
		for(i=0;i<n;i++){
			int c,d,x,y;
			scanf("%d %d %d %d",&c,&d,&x,&y);
			if(d==0)for(j=0;j<4;j++)for(int k=0;k<2;k++)ib[x+j-1][y+k-1]=c;
			if(d==1)for(j=0;j<2;j++)for(int k=0;k<4;k++)ib[x+j-1][y+k-1]=c;
		}
		if(search(xs-1,ys-1,ib[xs-1][ys-1]))printf("OK\n");
		else printf("NG\n");
	}
}

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

void solve(vector<vector<int> > &v,int x,int y,int c,int w,int h){
  if(x<1||y<1||w<x||h<y)return;
  if(v[y][x]!=c)return;
  v[y][x]=6;
  solve(v,x+1,y,c,w,h);
  solve(v,x-1,y,c,w,h);
  solve(v,x,y-1,c,w,h);
  solve(v,x,y+1,c,w,h);
}

int main(void){
  int w,h;
  while(cin>>w>>h,w||h){
    int xs,ys,xg,yg,n;
    vector<vector<int> > field(101);
    for(int i=0;i<101;++i)field[i].resize(101);
    cin>>xs>>ys>>xg>>yg>>n;
    for(int i=0,c,d,x,y;i<n;++i){
      cin>>c>>d>>x>>y;
      if(d){
        for(int j=y;j<y+4;++j)
          for(int k=x;k<x+2;++k)
            field[j][k]=c;
      }else{
        for(int j=y;j<y+2;++j)
          for(int k=x;k<x+4;++k)
            field[j][k]=c;
      }
    }
    solve(field,xs,ys,field[ys][xs],w,h);
    //for(int i=1;i<=h;++i){for(int j=1;j<=w;++j) cerr<<field[i][j]<<" ";cerr<<endl;}
    cout<<((field[yg][xg]==6)?"OK":"NG")<<endl;
  }
  return 0;
}

C++: #include <iostream>
int m[101][101],w,h,r,gx,gy;
void dfs(int x,int y,int c){
	if(!(x-gx)&&!(y-gy))r=1;
	if(x>1&&m[x-1][y]==c)m[x-1][y]=0,dfs(x-1,y,c);
	if(x<=w&&m[x+1][y]==c)m[x+1][y]=0,dfs(x+1,y,c);
	if(y>1&&m[x][y-1]==c)m[x][y-1]=0,dfs(x,y-1,c);
	if(y<=h&&m[x][y+1]==c)m[x][y+1]=0,dfs(x,y+1,c);
	return ;
}

int main(){
	//whÍ{[hÌå«³AnÍubNÌÂ
	int n,c,d,sx,sy,bx,by;
	
	while(std::cin>>w>>h,w&&h){
		for(int y=0;y<101;y++){
			for(int x=0;x<101;x++){
				m[x][y] = 0;
			}
		}
		r=0;
		std::cin>>sx>>sy;
		std::cin>>gx>>gy;
		std::cin>>n;
		for(int i=0;i<n;i++){
			std::cin>>c>>d>>bx>>by;
			int bw,bh;
			d?bw=2,bh=4:bh=2,bw=4;
			for(int y=by;y<=by+bh;y++){
				for(int x=bx;x<=bx+bw;x++){
					m[x][y] = c;
				}
			}
		}
		if(m[sx][sy])dfs(sx,sy,m[sx][sy]),m[sx][sy] = 0;
		if(r)std::cout<<"OK"<<std::endl;
		else{std::cout<<"NG"<<std::endl;}
	}
	return 0;
}