import java.io.BufferedReader;
import java.io.InputStreamReader;


public class No172 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO 自動生成されたメソッド・スタブ
                try {
            BufferedReader br = new BufferedReader(new InputStreamReader(
                    System.in));
            String[] tmpArray = br.readLine().split(" ");
            int x = Integer.parseInt(tmpArray[0]);
            int y = Integer.parseInt(tmpArray[1]);
            int r = Integer.parseInt(tmpArray[2]);

            int ans = (int) Math.ceil(Math.abs(x) + Math.abs(y) + Math.sqrt(2) * r);

            System.out.println(ans);
        } catch (Exception e) {
            System.err.println("Error:" + e.getMessage());
        }
    }

}