program project1;

var
    a, b, q, k, min, l, num, res: QWord;



function NumOfDel(k: qword): qword;
var
    num,p: qword;

begin
    num:=0;
    p := k;
    while b div k > 0 do
    begin
        num += b div k - ((a - 1) div k);
        if k < ((high(qword)) div p) then
            k := k * p
        else
            break;
    end;
    result := num div l;
end;

begin
    Assign(input, 'input.txt');
    Assign(output, 'output.txt');
    reset(input);
    rewrite(output);


    Read(a, b, q);
    k := 2;
    min := high(QWord);
    while (q div k > k) do
    begin
        if (q mod k = 0) then
        begin
            l := 0;
            while (q mod k = 0) and (q > 1) do
            begin
                l := l + 1;
                q := q div k;
            end;
            res := NumOfDel(k);
            if min > res then
                min := res;
            res := 0;
        end;
        k := k + 1;

    end;
    if (q > 1) then
    begin
        l := 1;
        res:=NumOfDel(q);
        if (min > res) then
        begin
            min := res;
        end;
    end;
    Write(min);
    readln;
    readln;
end.