{programmer:mogtaba amirzade 
url http:\\www.ifjam.com
}
 program p7(input,output);
var {13}
i,n:integer;
s:longint;
begin
readln(n);
s:=1;
i:=1;
repeat
s:=s*i;
i:=i+1;
until i>n;
writeln(s);
readln
end.