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

    if(x == xg && y == yg){
        ans = true;
        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;

        int n;
        cin >> n;
        rep(i,n){
            int c,d,x,y;
            cin >> c >> d >> 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");
        }
    }
}

C++: #include <iostream>
#include <stdio.h>
#include <queue>
using namespace std;
class node{
public:
	int x,y;
	void set(int xx,int yy){
		x = xx;
		y = yy;
	}
	bool check(int w,int h){
		if(x>=0&&y>=0){
			if(x<=w&&y<=h) return true;
		}
		return false;
	}
	
};

int main(){
	int w,h;
	w=h=1;
	while(w!=0||h!=0){
		int xs,ys,xg,yg,n,c,dir,x,y;
		int i,j;
		int color[101][101];
		int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
		bool visited[101][101];
		queue<node> q;
		node a;
		scanf("%d%d",&w,&h);
		scanf("%d%d",&xs,&ys);
		scanf("%d%d",&xg,&yg);
		scanf("%d",&n);
	
		while(n--){
			scanf("%d%d%d%d",&c,&dir,&x,&y);
			if(dir==0){
				for(i=0;i<2;i++){
					for(j=0;j<4;j++) color[x+j][y+i] = c;
				}
			}
			else{
				for(i=0;i<2;i++){
					for(j=0;j<4;j++) color[x+i][y+j] = c;
				}
			}
		}
		a.set(xs,ys);
		q.push(a);
		visited[a.x][a.y]=true;
		while(!q.empty()){
			a = q.front();
			q.pop();
			for(int i=0;i<4;i++){
				a.x += dx[i];
				a.y += dy[i];
				if(!a.check(w,h)&&(color[xs][ys]==color[a.x][a.y])&&!visited[a.x][a.y]){
					q.push(a);
					if(a.x==xg&&a.y==yg) break;
					visited[a.x][a.y] = true;
				}
			}
		}
		if(visited[xg][yg]) printf("OK\n");
		else printf("NG\n");
	}

	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int main() {
    int H, W;
    while (cin >> W >> H, H || W) {
        int sx, sy, gx, gy;
        cin >> sy >> sx >> gy >> gx;
        // sx--, sy--, gx--, gy--;
        int M;
        cin >> M;
        vector<vector<int> > d(H+1, vector<int>(W+1));
        vector<vector<int> > used(H+1, vector<int>(W+1));

        for (int i = 0; i < M; i++) {
            int c, dir, x, y;
            cin >> c >> dir >> y >> x;
            // x--, y--;
            if (!dir) {
                for (int j = 0; j < 2; j++) {
                    for (int k = 0; k < 4; k++) {
                        d[x + j][y + k] = c;
                    }
                }
            } else {
                for (int j = 0; j < 4; j++) {
                    for (int k = 0; k < 2; k++) {
                        d[x + j][y + k] = c;
                    }
                }
            }
        }

        for (auto i : d) {
            for (auto j : i) cout << j;
            cout << endl;
        }

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

        queue<int> qx, qy;
        qx.push(sx);
        qy.push(sy);

        while (qx.size()) {
            int x = qx.front(); qx.pop();
            int y = qy.front(); qy.pop();

            if (used[x][y]) continue;
            used[x][y] = 1;

            for (int i = 0; i < 4; i++) {
                int nx = x + dx[i];
                int ny = y + dy[i];

                if (0 <= nx && nx <= H && 0 <= ny && ny <= W && !used[nx][ny] && d[x][y] == d[nx][ny]) {
                    qx.push(nx);
                    qy.push(ny);
                }
            }
        }

        if (used[gx][gy]) cout << "OK" << endl;
        else cout << "NG" << endl;
    }

    return 0;
}