Fast.java

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;

public class NightChanges {

	private static Reader in;
	private static PrintWriter out;
    
	public static void main(String[] args) throws IOException {

		in = new Reader();
		out = new PrintWriter (System.out, true);
		//------------
		
		
		
		out.close();
		in.close();
	}

	static class Reader {
	    final private int BUFFER_SIZE = 1 << 16;
	    private DataInputStream din;
	    private byte[] buffer;
	    private int bufferPointer, bytesRead;
	    public Reader(){
	        din=new DataInputStream(System.in);
	        buffer=new byte[BUFFER_SIZE];
	        bufferPointer=bytesRead=0;
	    }

	    public Reader(String file_name) throws IOException{
	        din=new DataInputStream(new FileInputStream(file_name));
	        buffer=new byte[BUFFER_SIZE];
	        bufferPointer=bytesRead=0;
	    }

	    public String readLine() throws IOException{
	        byte[] buf=new byte[64]; // line length
	        int cnt=0,c;
	        while((c=read())!=-1){
	            if(c=='\n')break;
	            buf[cnt++]=(byte)c;
	        }
	        return new String(buf,0,cnt);
	    }

	    public int nextInt() throws IOException{
	        int ret=0;byte c=read();
	        while(c<=' ')c=read();
	        boolean neg=(c=='-');
	        if(neg)c=read();
	        do{ret=ret*10+c-'0';}while((c=read())>='0'&&c<='9');
	        if(neg)return -ret;
	        return ret;
	    } 

	    public long nextLong() throws IOException{
	        long ret=0;byte c=read();
	        while(c<=' ')c=read();
	        boolean neg=(c=='-');
	        if(neg)c=read();
	        do{ret=ret*10+c-'0';}while((c=read())>='0'&&c<='9');
	        if(neg)return -ret;
	        return ret;
	    }

	    public double nextDouble() throws IOException{
	        double ret=0,div=1;byte c=read();
	        while(c<=' ')c=read();
	        boolean neg=(c=='-');
	        if(neg)c = read();
	        do {ret=ret*10+c-'0';}while((c=read())>='0'&&c<='9');
	        if(c=='.')while((c=read())>='0'&&c<='9')
	            ret+=(c-'0')/(div*=10);
	        if(neg)return -ret;
	        return ret;
	    }
	    
	    public char nextChar() throws IOException{
	        byte c=read();
	        while(c<=' ')c=read();
	        return (char)c;
	    }
	    
	    private void fillBuffer() throws IOException{
	        bytesRead=din.read(buffer,bufferPointer=0,BUFFER_SIZE);
	        if(bytesRead==-1)buffer[0]=-1;
	    }
	    
	    private byte read() throws IOException{
	        if(bufferPointer==bytesRead)fillBuffer();
	        return buffer[bufferPointer++];
	    }
	    
	    public void close() throws IOException{
	        if(din==null) return;
	        din.close();
	    }
	}
}