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>
using namespace std;

int weight, hight;
int g[101][101];
int sc;
int sx, sy, gx, gy;
bool flag = false;
const int vx[4] = {0, 0, -1, 1};
const int vy[4] = {1, -1, 0, 0};

void dfs(int x, int y){
    if(x == gx && y == gy){
        flag = true;
        return;
    }

    for(int i = 0;i < 4;i++){
        int nx = x + vx[i];
        int ny = y + vy[i];
        
        if(nx >= 0 && nx < weight && ny >= 0 && ny < hight && g[ny][nx] == sc){
            g[y][x] = 8;
            dfs(nx, ny);
        }
    }
}

void disp(){
    for(int i = 0;i < hight;i++){
        for(int j = 0;j < weight;j++){
            cout << g[i][j];
        }cout << endl;
    }
}

int main(){
    int dn, c, d, x, y;
    
    while(cin >> weight >> hight){
        if(weight == 0 && hight == 0){
            break;
        }
        
        g[101][101] = {};
        
        cin >> sx >> sy >> gx >> gy >> dn;
        
        for(int i = 0;i < dn;i++){
            cin >> c >> d >> x >> y;
            
            if(d == 0){
                for(int h = 0;h < 2;h++){
                    for(int w = 0;w < 4;w++){
                        g[y+h][x+w] = c;
                    }
                }
            }else{
                for(int h = 0;h < 4;h++){
                    for(int w = 0;w < 2;w++){
                        g[y+h][x+w] = c;
                    }
                }
            }
        }
        
        sc = g[sy][sx];
        flag = false;
        dfs(sx, sy);
        
        if(flag){
            cout << "OK" << endl;
        }else{
            cout << "NG" << endl;
        }
    }
    
    return 0;
}

C++: #include <bits/stdc++.h>

#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define MAX 101

using namespace std;

int field[MAX][MAX];
bool went[MAX][MAX];
int w, h;
int sx, sy, gx, gy;
int scol;
const int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};

bool dfs(int x, int y) {
	went[y][x] = true;
	if(x == gx && y == gy) return true;
	rep(i, 4) {
		int nx = x + dx[i];
		int ny = y + dy[i];
		if(nx <= w && nx > 0 && ny <= h && ny > 0 && !went[ny][nx]) {
			if(field[ny][nx] == scol) dfs(nx, ny);
		}
	}
}

int main() {
	while(cin >> w >> h, w || h) {
		memset(field, 0, sizeof(field));
		memset(went, false, sizeof(went));
		int n;
		cin >> sx >> sy >> gx >> gy;
		cin >> n;
		rep(i, n) {
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			rep(i, (d ? 4 : 2)) rep(j, (d ? 2 : 4)) field[y + i][x + j] = c;
		}
		/*rep(i, h) {
			rep(j, w) cout << field[i][j] << " ";
			cout << endl;
		}*/
		scol = field[sy][sx]; 
		if(dfs(sx, sy) && scol != 0) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
	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 >> sx >> sy >> gx >> gy;
        // sx--, sy--, gx--, gy--;
        int M;
        cin >> M;
        vector<vector<int> > d(W+1, vector<int>(H+1));
        vector<vector<int> > used(W+1, vector<int>(H+1));

        for (int i = 0; i < M; i++) {
            int c, dir, x, y;
            cin >> c >> dir >> x >> y;
            // 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;
                    }
                }
            }
        }

        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;
}