take an email i.e. [email protected] and Parse Email by '@' and '.com'.

import java.util.*;

public class HelloWorld {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
String str=sc.next();
char ch[]=str.toCharArray();
int n1=str.indexOf('@');
int n2=str.indexOf('.');
StringBuilder user=new StringBuilder();
StringBuilder company=new StringBuilder();
for(int i=0;i<ch.length;i++)
{
if(i>=0 && i<n1)
{
user.append(ch[i]);
}
else if(i>n1 && i<n2)
{
company.append(ch[i]);
}
if(i>n2)
{
break;
}
}
String s1=user.toString();
s1=s1.substring(0,1).toUpperCase()+s1.substring(1);
String s2=company.toString();
s2=s2.substring(0,1).toUpperCase()+s2.substring(1);
System.out.println("Hi "+s1+", Welcome to "+s2);
}
}