from collections import defaultdict, deque, Counter
from heapq import heapify, heappop, heappush
import math
from copy import deepcopy
from itertools import combinations, permutations, product, combinations_with_replacement
from bisect import bisect_left, bisect_right

import sys

def input():
    return sys.stdin.readline().rstrip()
def getN():
    return int(input())
def getNM():
    return map(int, input().split())
def getList():
    return list(map(int, input().split()))
def getListGraph():
    return list(map(lambda x:int(x) - 1, input().split()))
def getArray(intn):
    return [int(input()) for i in range(intn)]

mod = 10 ** 9 + 7
MOD = 998244353
# sys.setrecursionlimit(10000000)
inf = float('inf')
eps = 10 ** (-15)
dy = [0, 1, 0, -1]
dx = [1, 0, -1, 0]

#############
# Main Code #
#############

"""
x = 0なら余りは0
nCkは求められない　どんな数か？
Mの因数はいくつあるか？という問題　分子と分母でMの個数を数えてみる
nCk = n! / (n - r)!r! とすると簡単
8*7*6*5*4*3*2*1/3*2*1 * 5*4*3*2*1
"""

N, K, M = getNM()

def calc(x, m):
    tar = m
    res = 0
    while tar <= x:
        res += x // tar
        tar *= m
    return res

print(calc(N, M) - calc(N - K, M) - calc(K, M))