Program n5;
var p: real;
i,n: integer;
begin
p:=1;
readln(n);
for i:=1 to n do p:=p*(2*i)/(2*i+1);
writeln(p);
end.
Program n1;
var sum,k,a: integer;
begin
readln(a);
sum:=0;
k:=0;
while a<>0 do
begin
if (a>99) and (a<1000) then<br>begin
k:=k+1;
sum:=sum+a;
end;
readln(a);
end;
if k=0 then write('NO') else write(sum/k);
end.
Program n2;
var k,a: integer;
begin
readln(a);
k:=0;
while a<>0 do
begin
if (a>99) and (a<1000) and (a mod 4=0) then k:=k+1;<br>readln(a);
end;
write(k);
end.