N,K,M = map(int,input().split())
def f(l,r,x):
    al = (l + pow(M,x) -1) // pow(M,x)
    al = max(al,1)
    ar = r //pow(M,x)
    if ar >= 1 and al <= ar:
        return ar - al + 1
    else:
        return 0
def g(l,r):
    x = 1
    res = 0
    while pow(M,x) <= r:
        res += f(l,r,x)
        x += 1
    return res

up = g(N-K+1,N)
down = g(1,K)
print(up-down)