import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.math.BigDecimal;

public class Main {
    public static void main(String[] args) {
        var formatter = new DecimalFormat("#,###.##");
        var s = new DecimalFormatSymbols();
        s.setDecimalSeparator(',');
        s.setGroupingSeparator('.');
        formatter.setDecimalFormatSymbols(s);
        var numero = new BigDecimal("10000999999999999999100.69");
        System.out.println(formatter.format(numero));
    }
}