import java.io.IOException;

public class Main {

	public static void main(String[] args) {
		int x = nextInt();
		int y = nextInt();
		int r = nextInt();
		int dist = Math.abs(x) + Math.abs(y) + (int) Math.ceil((double) Math.sqrt(2) * r);
		System.out.println(dist);
	}

	static int nextInt() {
		int c;
		try {
			c = System.in.read();
			while (c != '-' && (c < '0' || c > '9'))
				c = System.in.read();
			if (c == '-')
				return -nextInt();
			int res = 0;
			while (c >= '0' && c <= '9') {
				res = res * 10 + c - '0';
				c = System.in.read();
			}
			return res;
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return -1;
	}

}