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

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		int x = Integer.parseInt(sa[0]);
		int y = Integer.parseInt(sa[1]);
		int z = Integer.parseInt(sa[2]);
		br.close();

		if (x > y + z) {
			System.out.println(y + z);
		} else if (x + z < y) {
			System.out.println(x + z);
		} else {
			System.out.println((x + y + z) / 2);
		}
	}
}