uses crt;

var i, n : integer; S : real;

begin

clrscr;

write('Nhap so n = '); readln(n);

while (5 >= n) or (n > 100) do

    begin

        write('Nhap so n = '); readln(n);

    end;

i := 1; S := 0;

while i <= n do

    begin

        S := S + (i * (i + 1)) / ((i + 2) * (i + 3));

        i := i + 1;

    end;

write('Tong S = ', S : 2 : 2);

readln

end.

uses crt;
var n, i: longint;
    sum: real;
begin
clrscr;
    readln(n);
    if (n <= 5) or (n > 100) then
        begin
            repeat
                readln(n);
            until (n > 5) and (n <= 100);
        end;
    for i:=1 to n do sum:=sum + ((i * (i + 1)) / ((i + 2) * (i + 3)));
    writeln(sum:0:2);
readln;
end.