Sum of Geometric Sequence

You are given three integers: a₁, a_n, and k. The first term of a geometric sequence is a₁ and each subsequent term is obtained by multiplying the previous term by k. Only the terms that are less than or equal to a_n are considered. Your task is to calculate the sum of all such terms.

The formula for the geometric sequence is given by:

[ a_i = a_{1} \times k^{(i-1)} ]

Sum the terms as long as a₁ \times k^{(i-1)} \leq a_n. Print the result to the standard output.

inputFormat

The input consists of a single line containing three space-separated integers:

• a₁: The first term of the sequence.
• a_n: The upper bound (inclusive).
• k: The common ratio.

You can assume that a₁, a_n, and k are positive integers.

outputFormat

The output is a single integer: the sum of all terms in the sequence that do not exceed a_n.

## sample

2 16 2

30

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