#include<iostream>
#include<cmath>
#include<algorithm>

int main() {
	int x, y, r;

	std::cin >> x >> y >> r;

	int a; //傾き
	if ((x < 0 && y > 0) || (x > 0 && y < 0)) {
		a = 1;
	}else {
		a = -1;
	}

	long long a2 = -4;
	long long b = (y - a * x) * 4;
	long long c = 8 * r * r - 4 * x * x - 4 * y * y + 8 * a * x * y;

	long long result = (-b + sqrt(b * b - a2 * c)) / a2;
	long long result2 = (-b - sqrt(b * b - a2 * c)) / a2;

	int max = std::max(abs(result), abs(result2));

	std::cout << max + 1 << std::endl;
	return 0;
}