uses crt;
var a : integer;
p : extended;
F : text;
begin
clrscr;
assign(F,'input.txt');
reset(F);
p:=1;
while not eof(F) do
begin
read(f,a);
if a<34 then p:=p*a;
end;
close(F);
if p > 0 then p := exp(1/3*ln(p)) else if p < 0 then p := - exp (1/3*ln(-p)) else p := 0;
writeln(p:0:5);
readln;
end.