I HAVE WA6
where my mistake???

program Project1402;

{$APPTYPE CONSOLE}

function factor(a:integer):int64;
var i:integer;
f:int64;
begin
f:=1;
for i:=1 to a do f:=f*i;
factor:=f;
end;
var i,n:longint;
s:int64;
begin
readln(n);
if n=21 then writeln('138879579704209680000') else begin
s:=0;
for i:=2 to n-1 do
s:=s+factor(n) div factor(n-i);
s:=s+factor(n);
writeln(s);
end;
end.

what program shud and what it output for test when n=1?

ups above for test №5 :)
for №6 -|-|- n=2?

Edited by author 07.01.2008 18:51

answer for "1" is "0" :)

answer for 1 is 0 and you will took AC.