import java.io.*;
import java.util.*;

class Main {
	
	public static void out (Object o) {
		System.out.println(o);
	}
		
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		String[] line = br.readLine().split(" ");
		int x = Math.abs(Integer.parseInt(line[0]));
		int y = Math.abs(Integer.parseInt(line[1]));
		int r = Integer.parseInt(line[2]);
		
		double d = Math.sqrt(x * x + y * y) + r;
		d = 2 * d * d;
		
		for (int i = 1; ; i++) {
			if (i * i >= d) {
				out(i);
				break;
			}
		}
	}
}