pineapple

public class Sentence{
    private String sentence;
    public Sentence(String s){
        sentence = s;
    }
    public String reverse(){
        String ns = "";
        for(int i =sentence.length();i>0;i--){
            ns+=sentence.substring(i-1,i);
        }
        return ns;
    }
    public String noX(){
        String ns = "";
        for(int i =0;i<sentence.length();i++){
            if(sentence.substring(i,i+1).equals( "X")){
                ns+="";
            }
            else{
                ns+=sentence.substring(i,i+1);
            }
        }
        return ns;
    }
    public String endX(){
        String ns = "";
        int count = 0;
        for(int i =0;i<sentence.length();i++){
            if(sentence.substring(i,i+1).equals( "X")){
                count++;
                ns+="";
            }
            else{
                ns+=sentence.substring(i,i+1);
            }
        }
        for(int i =0;i<count;i++){
            ns+="X";
        }
        return ns;
    }
    public String ziper(String s1, String s2){
        String ns = "";
        for(int i =0;i<s2.length();i++){
            ns+=s1.substring(i,i+1) + s2.substring(i,i+1);
        }
        return ns;
    }
}