program p8_2_a;
uses crt;

function fs(n : integer) : real;
var k : integer; s: real;
begin
 k := 2; s := 1;
 repeat
  s := s + 1/sqrt(k);
  k := k + 1;
 until k > n;
 fs := s;
end;

var n : integer; s : real;
begin
 clrscr;

 writeln('pi*pi/6   = ', pi * pi / 6:2:20);
 s := fs(10);
 writeln('n = 10, s = ', s:2:20);
 s := fs(20);
 writeln('n = 20, s = ', s:2:20);
 s := fs(30);
 writeln('n = 30, s = ', s:2:20);

readln;
end.