from math import sqrt
n,k,m = map(int,input().split())

def is_small(a):
    if float(a)*(a+k)*(a+2*k) > 2e18: return False
    else: return a*(a+k)*(a+2*k) <= n

from collections import Counter
d = Counter()
for a in range(1,10**6+1):
    if is_small(a): d[a*(a+k)*(a+2*k)] += 1
    else: break

def check(x): # a(a+k) = x なる a ある？
    v = int((sqrt(float(k)**2 + 4.0*x) - k)/2)
    for a in range(max(1,v-3),v+5):
        if a >= 1 and a*(a+k)==x: return True
        if a*(a+k) > x: return False
    return False

ans = 0
for x,v in d.items():
    if v == m and not check(x):
        ans += 1
    elif v == m-1 and check(x):
        ans += 1

if m == 1:
    v = int((sqrt(float(k)**2 + 4.0*x) - k)/2)
    for a in range(max(1,v-3),v+5):
        if a*(a+k) > n: break
    ans += a-1
    for x in d:
        if check(x): ans -= 1

print(ans)