a, b, c = map(int, input().split())
b *= 2
c *= 4
if a < 0:
    a, b, c = -a, -b, -c

def f(x):
    return a * x * x + b * x + c >= 0

neg = -b // 2
d = 1
while not f(neg - d):
    d *= 2
nonneg = neg - d
while abs(nonneg - neg) > 1:
    mid = (nonneg + neg) // 2
    if f(mid):
        nonneg = mid
    else:
        neg = mid

alpha = nonneg

neg = -b // 2
d = 1
while not f(neg + d):
    d *= 2
nonneg = neg + d
while abs(nonneg - neg) > 1:
    mid = (nonneg + neg) // 2
    if f(mid):
        nonneg = mid
    else:
        neg = mid
beta = nonneg

if alpha % 2: alpha -= 1
if beta % 2: beta += 1
print((beta - alpha) // 2 - 1)