n, k, m = map(int,input().split())

def count(x):
    #1*2*...*xをmで割り切る回数
    ret = 0
    rui = 0
    for i in range(1000, -1, -1):
        now = x // (m ** i)
        ret += now
        rui += now
    return ret

print(count(n) - count(k) - count(n - k))