/* package whatever; // don't place package name! */

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

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
    	String sentence = "hello world! 722";
    	String str = sentence.replaceAll("[a-zA-Z]", "@");
    	System.out.println(str); // "@@@@@ @@@@@! 722"
	}
}