import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.*;
 
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        

	int a = Integer.parseInt(in.next()), b = Integer.parseInt(in.next()),c = Integer.parseInt(in.next());

	if(b == 0) out.println(0);
	int count = 0;
	while(b > 0 && c >1){
		count+=3;
		b--;
		c-=2;

	}

	while(a > 0 && b > 1){
		count+=3;
		a--;
		b-=2;
		
	
	}

	out.println(count);
		
	out.close();
    }
}
