Define the function $f(x)$ that equals to the number of divisors of $x$. Given two integers $a$ and $b~(a \le b)$, calculate the sum $f(a) + f(a + 1) + ... + f(b)$. \InputFile Each line contains two integers $a$ and $b~(1 \le a \le b ≤ 2^{31} - 1)$. The input is terminated by a line with $a = b = 0$. \OutputFile For each test case print in a separate line the value of $f(a) + f(a + 1) + ... + f(b)$.