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 <algorithm>
#include <cassert>
#include <cctype>
#include <complex>
#include <cstdio>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

int w,h,sx,sy,gx,gy,d[101][101],dx[4]={1,0,-1,0},dy[4]={0,1,0,-1},C;
int field[101][101];
const int INF=9999999;
typedef pair<int,int> P;

void bfs(){
	queue<P> que;
	for(int i=1;i<=h;i++)for(int j=1;j<=w;j++)d[i][j]=INF;
	que.push(P(sy,sx));
	d[sy][sx]=0;
	while(!que.empty()){
		P p=que.front(); que.pop();
		if(p.first==gy&&p.second==gx)break;
		for(int i=0;i<4;i++){
			int ny=p.first+dx[i],nx=p.second+dy[i];
			if(1<=ny&&ny<=h&&1<=nx&&nx<=w&&field[ny][nx]==C&&d[ny][nx]==INF){
			que.push(P(ny,nx));
			d[ny][nx]=d[p.first][p.second]+1;
			}
		}
	}
	if(d[gy][gx]==INF)cout<<"NG"<<endl;
	else cout<<"OK"<<endl;
}

int main() {
	while(cin>>h>>w){
		if(!h)return 0;
		int n,c,di,x,y;
		cin>>sx>>sy>>gx>>gy>>n;
		for(int i=1;i<=h;i++)for(int j=1;j<=w;j++)field[i][j]=0;
		for(int i=0;i<n;i++){
			cin>>c>>di>>x>>y;
			for(int j=y;j<=y+2+di*2;j++)for(int k=x;k<=x+2+!di*2;k++)field[j][k]=c;
		}
		C=field[1][1];
		bfs();
	}
}

C++: #include <iostream>

using namespace std;

int table[100][100];
int memo[100][100];

int w, h;
int xs, ys, xg, yg;
int n;

void solve(int xs, int ys, int c)
{
	if( memo[xs][ys] ) {
		return;
	}

	if( !( 0 < xs && xs < w+1 && 0 < ys && ys < h+1 && table[xs][ys] == c ) ) {
		memo[xs][ys] = 1;
		return;
	}
	
	if( xs == xg && ys == yg ) {
		memo[xs][ys] = 1;
		cout << "OK" << endl;
		throw "OK";
	}

	memo[xs][ys] = 1;	

	solve(xs+1, ys, c);
	solve(xs, ys+1, c);	
	solve(xs-1, ys, c);
	solve(xs, ys-1, c);

	return;
}

int main(int argc, char* argv[])
{
	while(1) {

		for( int i = 0; i < 100; i++ ) {
			for( int j = 0; j < 100; j++ ) {
				table[i][j] = 0;
				memo[i][j] = 0;
			}
		}		

		cin >> w >> h;

		if( w == 0 && h == 0 )
			break;
			
		cin >> xs >> ys;
		cin >> xg >> yg;
		cin >> n;

		for( int i = 0; i < n; i++ ) {

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

			if( d == 0 ) {

				table[x][y] = c;
				table[x][y+1] = c;

				table[x+1][y] = c;
				table[x+1][y+1] = c;

				table[x+2][y] = c;
				table[x+2][y+1] = c;

				table[x+3][y] = c;
				table[x+3][y+1] = c;																
				

			} else {

				table[x][y] = c;
				table[x+1][y] = c;

				table[x][y+1] = c;
				table[x+1][y+1] = c;

				table[x][y+2] = c;
				table[x+1][y+2] = c;
				
				table[x][y+3] = c;
				table[x+1][y+3] = c;								
			}
		}

		try {
			if( table[xs][ys] )
				solve(xs, ys, table[xs][ys]);
			cout << "NG" << endl;
		} catch(...) {
		}
	}

    return 0;
}

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

int field[101][101];
int dx[] = {0, 1, 0, -1};
int dy[] = {-1, 0, 1, 0};
int heights[] = {2, 4};
int widths[] = {4, 2};
int w, h;
int gx, gy;

bool isMaze(int y, int x) {
    if (y == gy && x == gx) {
        return true;
    }
    int c = field[y][x];
    field[y][x] = 0;
    for (int i = 0; i < 4; i++) {
        int ny = y + dy[i], nx = x + dx[i];
        if (1 <= ny && ny <= h && 1 <= nx && nx <= w && field[ny][nx] == c && isMaze(ny, nx)) {
            return true;
        }
    }
    return false;
}

int main() {
    while (true) {
        cin >> w >> h;
        if ((w | h) == 0) {
            break;
        }
        int sx, sy, n;
        cin >> sx >> sy >> gx >> gy >> n;
        memset(field, 0, sizeof(field));
        while (n--) {
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            for (int i = 0; i < heights[d]; i++) {
                for (int j = 0; j < widths[d]; j++) {
                    field[y + i][x + j] = c;
                }
            }
        }
        if (field[sy][sx] > 0 && field[sy][sx] == field[gy][gx] && isMaze(sy, sx)) {
            cout << "OK" << endl;
        } else {
            cout << "NG" << endl;
        }
    }
}

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

int F[102][102];
int cnt=0;

void DFS(int XS, int YS, int XG, int YG, int e){
	if(F[XS][YS]!=e){
		return;
	}
	if(XS==XG&&YS==YG){
		cnt++;
	}
	F[XS][YS]=0;

	DFS(XS-1,YS  ,XG,YG,e);
	DFS(XS  ,YS+1,XG,YG,e);
	DFS(XS+1,YS  ,XG,YG,e);
	DFS(XS  ,YS-1,XG,YG,e);
}

int main(){
	while(true){
		int w,h;
		cin>>w>>h;
		if(w==0&&h==0)
			break;
		for(int i=0; i<=102; i++){
			for(int j=0; j<=102; j++){
				F[j][i]=0;
			}
		}
		cnt=0;
		int xs,ys;
		cin>>xs>>ys;
		int xg,yg;
		cin>>xg>>yg;
		int n;
		cin>>n;
		int c[n];
		int d[n], x[n], y[n];
		for(int i=0; i<n; i++){
			cin>>c[i]>>d[i]>>x[i]>>y[i];
		}
		for(int i=0; i<n;  i++){
			if(d[i]==0){
				F[x[i]  ][y[i]]=c[i];	F[x[i]  ][y[i]+1]=c[i];
				F[x[i]+1][y[i]]=c[i];	F[x[i]+1][y[i]+1]=c[i];
				F[x[i]+2][y[i]]=c[i];	F[x[i]+2][y[i]+1]=c[i];
				F[x[i]+3][y[i]]=c[i];	F[x[i]+3][y[i]+1]=c[i];
			}
			else{
				F[x[i]][y[i]  ]=c[i];	F[x[i]+1][y[i]  ]=c[i];
				F[x[i]][y[i]+1]=c[i];	F[x[i]+1][y[i]+1]=c[i];
				F[x[i]][y[i]+2]=c[i];	F[x[i]+1][y[i]+2]=c[i];
				F[x[i]][y[i]+3]=c[i];	F[x[i]+1][y[i]+3]=c[i];
			}
		}
		if(F[xs][ys]!=0){
			if(F[xg][yg]!=0){
				DFS(xs,ys,xg,yg,F[xs][ys]);
			}
		}
		if(cnt==1){
			cout<<"OK"<<endl;
		}
		else{
			cout<<"NG"<<endl;
		}
	}
	return 0;
}