import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int c = sc.nextInt();
        int d = sc.nextInt();
        double left = 0;
        double right = Math.min(c / 3.0 * 4, d * 4);
        for (int i = 0; i < 1000000; i++) {
            double m1 = (left * 2 + right) / 3;
            double m2 = (left + right * 2) / 3;
            if (getIncome(m1, c, d) < getIncome(m2, c, d)) {
                left = m1;
            } else {
                right = m2;
            }
        }
        System.out.println(new java.math.BigDecimal(getIncome(left, c, d)).toPlainString());
    }
    
    static double getIncome(double a, double c, double d) {
        c -= a * 3 / 4;
        d -= a / 4;
        double b = Math.min(c / 2 * 7, d / 5 * 7);
        return a * 1000 + b * 2000;
    }
    
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}