public class learn {
    public static void main(String args[]) throws IOException
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String S;String S2 ="";
        System.out.println("Enter String");
               S=br.readLine();

        for(int i=0;i<S.length();i++){
            Boolean check=false;

            for(int j=i+1;j<S.length();j++)
            {

            if(S.charAt(i)==S.charAt(j)){
                check=true;
                break;
            }
            else
                S2= S2+S2.concat(String.valueOf(S.charAt(i)));

                System.out.pr`enter code here`int(S2);


            }}