program test;var x: integer;var y: integer;var factSred : real;Function fact(arg:integer) : integer;var i: integer;var r: integer;Begin i:=1; r:=1; while i<=arg dobegin r := r*i; i := i + 1;end;fact := r;End;begin readln(x); readln(y);factSred:=(fact(x)+fact(y))/2; writeln(factSred:0:2);end.
program test;
var x: integer;
var y: integer;
var factSred : real;
Function fact(arg:integer) : integer;
var i: integer;
var r: integer;
Begin
i:=1;
r:=1;
while i<=arg do
begin
r := r*i;
i := i + 1;
end;
fact := r;
End;
begin
readln(x);
readln(y);
factSred:=(fact(x)+fact(y))/2;
writeln(factSred:0:2);
end.