import java.awt.Point;
import java.awt.Rectangle;
import java.awt.geom.Rectangle2D;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.*;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentSkipListSet;

public class Main {
	public static final int C =  1000000007;
	static final int CY = 1000000000;

	public void calc() {
		StringBuilder sb = new StringBuilder();
		BufferedInputStream bs = new BufferedInputStream(System.in);
		Scanner sc = new Scanner(bs);

		int n = sc.nextInt();
		
		int ans = 0;
		//double ans = 0.0;

		ans = n + (n%2 == 1?1: 0);
		

		System.out.println(ans);

	}



	public static void main(String[] args) {
		Main main = new Main();
		main.calc();

	}
}