#define _USE_MATH_DEFINES

#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset
#include <cmath>		//sqrt, ceil. M_PI, pow, sin
#include <ios>			//fixed
#include <iomanip>		//setprecision
#include <sstream>		//stringstream
#include <numeric>		//gcd, assumlate
#include <random>		//randam_device
#include <limits>		//numeric_limits

using namespace std;
constexpr long long int D_MOD = 1000000007;

int main() {

	int x, y, r;
	cin >> x >> y >> r;

	double b = 2 * r / sqrt(2);
	int c = ceil(b);

	int ans;
	if (x == 0 && y == 0) { ans = c; }
	else if (x > 0 && y > 0) { ans = abs(x + y + c); }
	else if (x > 0 && y < 0) { ans = abs(x - y - c); }
	else if (x < 0 && y < 0) { ans = abs(x + y - c); }
	else { ans = abs(y - x + c); }

	cout << ans << endl;

	return 0;

}