# Poj Solution 1522

```http://poj.org/problem?id=1522

/* @author:zeropinzuo */
import java.io.*;
import java.util.*;

public class Main{
static Scanner cin;
static int count=0;
public static void main(String args[]){
cin = new Scanner(System.in);
int n;
while((n=cin.nextInt())!=0)
run(n);
}

static void run(int n){
Point start,end;
start = new Point(n, cin);
end   = new Point(n, cin);

ArrayList< PointSet> Mset = new ArrayList< PointSet>();

PointSet startSet = new PointSet();
PointSet endSet = new PointSet();

Point A,B;
PointSet setA=new PointSet(), setB=new PointSet();
while(true){
if(cin.hasNext("-1") == true){
cin.nextInt();
break;
}

setA = null;
setB = null;
A = new Point(n, cin);
B = new Point(n, cin);

for(PointSet set:Mset){
if(set.contains(A))
setA = set;
if(set.contains(B))
setB = set;
}

if((setA != null)&&(setB != null)){
if(setA != setB){
Mset.remove(setB);
}
}
else if(setA != null)
else if(setB != null)
else{
setA = new PointSet();
}

}

startSet = null;
endSet   = null;
for(PointSet set:Mset){
if(set.contains(start))
startSet = set;
if(set.contains(end))
endSet = set;
}

if(startSet == endSet)
System.out.println("Maze #"+(++count)+" can be travelled");
else
System.out.println("Maze #"+(++count)+" cannot be travelled");
}
}

class Point implements Comparable{
int num;

public Point(int n, Scanner cin){
num=0;
for(int i=0;i< n;i++)
num = 10*num+cin.nextInt();
}

public int compareTo(Object another){
Point p = (Point)another;

return this.num-p.num;
}
}

class PointSet extends TreeSet< Point>{

}
```
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