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 <bits/stdc++.h>
using namespace std;


bool b;

void dfs(const vector<vector<int> >& v ,int x , int y , int w , int h , int xg , int yg , int sc){
	if(x==xg&&y==yg) {b=true;return;}
	for(int i=0;i<4;++i){
		int dx[]={1,0,-1,0};
		int dy[]={0,1,0,-1};
		int tx=x+dx[i];
		int ty=y+dy[i];
		if(tx<=0||ty<=0||tx>w||ty>h) continue;
		if(v[tx][ty]!=sc || v[tx][ty]==0) continue;
		if(b) continue;
		dfs( v , tx,ty,w,h,xg,yg,sc);
	}
}

int main(){
	int w , h;
	while(cin >> w >> h , w||h){
		int xs , ys , xg , yg ;
		int n;
		b=false;
		vector<vector<int> > board(101);
		for(int i=0;i<101;++i) board[i].resize(101);
		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=0;k<2;++k){
					for(int j=0;j<4;++j){
						board[x+j][y+k]=c;
					}
				}
			} else {
				for(int k=0;k<4;++k){
					for(int j=0;j<2;++j){
						board[x+j][y+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>

int field[101][101];//y,x
bool flag;
int n,a,sx,sy,gx,gy,col;

void erase(){
	for(int i=0; i<101; i++)
		for(int j=0; j<101; j++)
			field[i][j] = 0;
}

void DFS(int x, int y){
	int xx = x;
	int yy = y;

	if(xx == gx && yy == gy){
		flag = true;
		return;
	}

	xx++;
	if(field[yy][xx] == col)
		DFS(xx, yy);
	if(flag)
		return;

	xx--;
	yy++;
	if(field[yy][xx] == col)
		DFS(xx, yy);
	if(flag)
		return;
		
	xx--;
	yy--;
	if(field[yy][xx] == col)
		DFS(xx, yy);
	if(flag)
		return;
			
	xx++;
	yy--;
	if(field[yy][xx] == col)
		DFS(xx, yy);
}

int main(){
	int c,d,bx,by;
	using std::cin;
	while(true){
		flag = false;
		erase();
		cin >> n >> a;
		if(!n && !a)
			return 0;
		cin >> sx >> sy;
		cin >> gx >> gy;
		cin >> n;
		for(int i=0; i<n; i++){
			cin >> c >> d >> bx >> by;
			if(d==0){
				for(int h=by; h<by+2; h++)
					for(int k=bx; k<bx+4; k++)
						field[h][k] = c;
			}
			else{
				for(int h=by; h<by+4; h++)
					for(int k=bx; k<bx+2; k++)
						field[h][k] = c;
			}
		}
		col = field[gy][gx];
		DFS(sx, sy);
		if(flag)
			std::cout << "OK\n";
		else
			std::cout << "NG\n";
	}
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
#define INF 1010001000
#define loop(i, n) for (int i = 0; i < n; i++)
#define mp make_pair
typedef pair<int, int> i_i;

bool dfs(vector<vector<int> > &g);

int sx, sy, gx, gy;
int n, m; 
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};

int main()
{

while(cin >> n >> m,(n|m)){
 m++; n++;
 vector<vector<int> > graph(m,vector<int>(n,0));
 
 cin>>sx>>sy>>gx>>gy;
 int bl;  cin>>bl;
 loop(i, bl){
  int a,b,c,t; cin>>a>>b>>c>>t;
  if(b){
   for(int j=t;j<t+2;j++){
    for(int k=c;k<c+4;k++){
     graph[k][j] = a;
    }
   } 
  } else {
   for(int j=c;j<c+2;j++){
    for(int k=t;k<t+4;k++){
     graph[k][j] = a;
    }
   }
  }
 }
cout << (dfs(graph)) ? "OK" : "NG" << endl;
}
return 0;
}

bool dfs(vector<vector<int> > &g) {
int cl = g[sx][sy];
vector<vector<bool> > vsed(m,vector<bool>(n,false));
queue<i_i > q;
q.push(mp(sx,sy));
while(!q.empty()){
int x = q.top().first, y = q.top().second;
q.pop();
if(x == gx && y == gy){
return true;
}
if(vsed[x][y]){
continue;
} else {
vsed[x][y]=true;
}

loop(i, 4) {
int nx = x +dx[i], ny = y +dy[i];
if(0<nx && nx < n && 0<ny && ny < m){
if(g[nx][ny] == cl){
q.push(mp(nx,ny));
}
} 
}

}
return false;
}

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

int F[102][102];


int DFS(int Y,int X,int c){
  int cnt = 0;
  if(F[Y][X] != c){
    return 0;
  }

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


int main(){
  int w,h,xs,ys,xg,yg,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;

      for(int i=0;i<102;i++){
        for(int j=0;j<102;j++){
                F[i][j]=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 == 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(x == 8){
    cout << "OK" << endl;
  } else {
    cout << "NG" << endl;
  }
  }
}

C++: #include <iostream>
using namespace std;
 
int C[102][102];
int ans;
int xg,yg;
 
void meiro(int W,int H,int c){
  if(W==xg && H==yg){
    ans = 1;
    return;
  }
 
  if(C[W][H]!=c){
    return;
  }
 
  C[W][H] = 0;
 
  meiro(W-1,H  ,c);
  meiro(W  ,H+1,c);
  meiro(W+1,H  ,c);
  meiro(W  ,H-1,c);
}
 
int main(){
  while(1){
    for(int i=0;i<102;i++){
      for(int j=0;j<102;j++){
        C[i][j] = 0;
      }
    }
     
    int w,h;
    cin >> w >> h;
 
    if(w==0 && h==0){
      break;
    }
 
    int xs,ys;
    cin >> xs >> ys;
 
    cin >> xg >> yg;
 
    int n;
    cin >> n;
    int c,d,x,y;
 
    int cbase;
 
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
 
      if(d==0){
        for(int j=x;j<x+4;j++){
          for(int k=y;k<y+2;k++){
            C[j][k]=c;
          }
        }
      }
      if(d==1){
        for(int j=x;j<x+2;j++){
          for(int k=y;k<y+4;k++){
            C[j][k]=c;
          }
        }
      }
    }
    ans = 0;
 if(C[xs][ys] == 0){
      cout << "NG" << endl;
      continue;
    }
    meiro(xs,ys,C[xs][ys]);
   
    if(ans==1){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }
 
  return 0;
}