Multifactorial

The k-multifactorial of n is denoted by fac_k(n) and is defined as the product of every positive number of the form n – k * x, x = 0, 1, 2, … .

A formal definition of multifactorial is:

fac_k(n) = n, if k ≥ n;

fac_k(n) = n * fac_k(n – k), if k < n;

You will be given n and k and have to evaluate the value of fac_k(n). If the result is strictly greater than 10¹⁸, you must print "overflow".

Specifications

Input

Two integers n and k (1 ≤ n, k ≤ 2 * 10⁹).

Output

The value of fac_k(n). If it is strictly greater than 10¹⁸, print "overflow".

Problem information

Time Limit: 1 seconds
Memory Limit: 64 MB
Balls for the passed test: 5
Complexity: 35% 51/78
Classes: Simple mathematics

Example

Example input

Sample 1
14 3

Sample 2
1000 2

Example output

Sample 1
12320

Sample 2
overflow

← MassiveNumbers

Problems

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