PAT 1031

简单题，字符串处理，注意index就可以了

import java.util.*;
import java.io.*;

class FastReader{
    BufferedReader reader;
    StringTokenizer tokenizer;
    
    public FastReader(InputStream stream){
        reader = new BufferedReader(new InputStreamReader(stream), 1 << 10);
        tokenizer = null;
    }
    
    public String next(){
        while (tokenizer == null || !tokenizer.hasMoreTokens()){
            try{
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (Exception e){
                throw new RuntimeException(e);
            }
        }
        
        return tokenizer.nextToken();
    }
    
    public long next_long(){
        return Long.parseLong(next());
    }
    
    public int next_int(){
        return Integer.parseInt(next());
    }
}

public class Main {
    public static void main(String[] args){
        FastReader reader = new FastReader(System.in);
        String process_str = reader.next();
        
        int size = process_str.length() + 2;
        int n1, n2, n3;
        
        n1 = n3 = size / 3;
        n2 = n1 + size % 3;
        size -= 2;
        
        StringBuilder white_space = new StringBuilder();
        for (int i = 0; i < n2 - 2; i++)
            white_space.append(' ');
        
        for (int i = 0; i < n1 - 1; i++)
            System.out.println(process_str.charAt(i) + white_space.toString() + process_str.charAt(size - i - 1));
        for (int i = n1 - 1; i <= size - n1; i++)
            System.out.print(process_str.charAt(i));
        System.out.println();
    }
}