Program vypocet;
uses crt;
var i : integer;
x:array[1..1000] of real;
s:real

begin
clrscr;
x[1]=1/6;
s:=0;
for i := 2 to 1000 do
begin
x[i]=x[i-1]*5/6
s=s+x[i];
end;
writeln(s:0:30);
readln;
end.