#include <cstdio>
#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <functional>
#include <queue>
#include <stack>
#include <cmath>
#include <iomanip>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define CLR(a) memset((a), 0 ,sizeof(a))
#define MCLR(a) memset((a), -1 ,sizeof(a))
#define SZ(a) (sizeof(a))
#define FILL(a,v) fill((int*)a,(int*)(a+(SZ(a)/SZ(*(a)))),v)

bool cheak(int x, int y, int xMax, int yMax)
{
	return x >= 0 && y >= 0 && xMax > x && yMax > y;
}
const int dx[4] = { -1, 0, 1, 0 }, dy[4] = { 0, 1, 0, -1 };
typedef pair<int, int> P;
typedef long long ll;
typedef unsigned long long ull;
const int mod = 1000000007;
const int INF = 2147483647;


int main()
{
	double x,y,r;
	cin >> x >> y >> r;

	double l = sqrt(x*x+y*y)+r;

	for (int i = 1; i < 1000; i++)
	{
		if (sqrt(double(i*i + i*i)) > l*2.0){
			cout << i+1 << endl;
			break;
		}
	}

	return 0;
}