@FunctionalInterface

interface MyFunctionalInterface $\{$

public Integer sqr$($int a$)$;

default String sqr$($String a$)\{$

return a $+$ a;

$\}$

$\}$

public class Test $\{$

public static void main$($String$[]$ args$)\{$

MyFunctionalInterface fi $=$ n $->\{$

return n $*$ n;

$\}$;

System.out.println$($fi$.$sqr$(5))$;

$\}$