#ifdef LOCAL111
#else
	#define NDEBUG
#endif
#include <bits/stdc++.h>
const int INF = 1e8;
using namespace std;

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define RBP(i,a) for(auto& i : a)
#ifdef LOCAL111
	#define DEBUG(x) cout<<#x<<": "<<(x)<<endl
#else
	#define DEBUG(x) true
#endif
#define F first
#define S second
#define SNP string::npos
#define WRC(hoge) cout << "Case #" << (hoge)+1 << ": "
#define rangej(a,b,c) ((a) <= (c) and (c) < (b))
#define rrangej(b,c) rangej(0,b,c)
template<typename T> void pite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}

typedef pair<int,int> P;
typedef long long int LL;
typedef unsigned long long ULL;
typedef pair<LL,LL> LP;

void ios_init(){
	//cout.setf(ios::fixed);
	//cout.precision(12);
#ifdef LOCAL111
	return;
#endif
	ios::sync_with_stdio(false); cin.tie(0);	
}

//library
#define  EPS (1e-10)
#define equal(a, b) (fabs((a) - (b)) < EPS)


class Point {
public:
	double x,y;
	
	Point(double x = 0,double y = 0): x(x), y(y) {}
	
	Point operator+ (const Point &p) { return Point(x + p.x, y + p.y); }
	Point operator- (const Point &p) { return Point(x - p.x, y - p.y); }
	Point operator* (double k) { return Point(x * k, y * k); }
	Point operator/ (double k) { return Point(x / k, y / k); }
	void operator+= (const Point &p) { x += p.x; y += p.y; }

	double norm() { return x*x + y*y; }
	double abs() { return sqrt(norm()); }

	bool operator< (const Point &p) const {
		return x != p.x ? x < p.x : y < p.y;
	}

	bool operator> (const Point &p) const {
		return x != p.x ? x > p.x : y > p.y;
	}

	bool operator== (const Point &p) const {
		return fabs(x - p.x) < EPS && fabs(y - p.y) < EPS;
	}

	bool operator!= (const Point &p) const {
		return !(Point(x,y) == p);
	}
};
//library

const int dx[] = {-1,1,-1,1};
const int dy[] = {-1,1,1,-1};

int main()
{
	ios_init();
	Point p;
	int r;
	cin >> p.x >> p.y >> r;
	Point pa[4];
	double rt = sqrt(2);
	rt = 1./rt;
	REP(i,4){
		pa[i] = p;
		pa[i].x += dx[i]*rt*r;
		pa[i].y += dy[i]*rt*r;
		DEBUG(pa[i].x); DEBUG(pa[i].y);
	}
	int di = 1;
	while(true){
		DEBUG(di);
		bool f = true;
		REP(i,4){
			REP(j,4){ 
				if(!((dy[j]*pa[i].y <= dy[j]*(dx[j]*pa[i].x+dy[j]*di)))){
					DEBUG(pa[i].y); DEBUG(pa[i].x);
					f = false;
					goto END;
				}
			}
		}
		END:
		if(f){
			cout << di << endl;
			break;
		}
		di++;
	}
	return 0;
}