var n,i: integer; p: real;
begin
readln(n);
p:=1;
for i:=1 to n do p:=p*(2*i)/(2*i+1);
writeln(p);
end.
var n,i: integer; p: real;
begin
readln(n);
p:=1;
for i:=1 to n do p:=p*(2*i)/(2*i+1);
writeln(p);
end.