A New Year party is not a New Year party without lemonade! As usual, you are expecting a lot of guests, and buying lemonade has already become a pleasant necessity.

Your favorite store sells lemonade in bottles of n different volumes at different costs. A single bottle of type i has volume 2i - 1 liters and costs ci roubles. The number of bottles of each type in the store can be considered infinite.

You want to buy at least L liters of lemonade. How many roubles do you have to spend?

Input

The first line contains two integers n and L (1 ≤ n ≤ 30; 1 ≤ L ≤ 109) — the number of types of bottles in the store and the required amount of lemonade in liters, respectively.

The second line contains n integers c1, c2, ..., cn (1 ≤ ci ≤ 109) — the costs of bottles of different types.

Output

Output a single integer — the smallest number of roubles you have to pay in order to buy at least L liters of lemonade.

Examples

Input

4 12
20 30 70 90


Output

150


Input

4 3
10000 1000 100 10


Output

10


Input

4 3
10 100 1000 10000


Output

30


Input

5 787787787
123456789 234567890 345678901 456789012 987654321


Output

44981600785557577

Note

In the first example you should buy one 8-liter bottle for 90 roubles and two 2-liter bottles for 30 roubles each. In total you'll get 12 liters of lemonade for just 150 roubles.

In the second example, even though you need only 3 liters, it's cheaper to buy a single 8-liter bottle for 10 roubles.

In the third example it's best to buy three 1-liter bottles for 10 roubles each, getting three liters for 30 roubles.
import sun.reflect.generics.tree.Tree;

import java.io.*;
import java.util.*;
import java.lang.*;


public class Main implements Runnable {
    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    public static void main(String args[]) throws Exception {
        new Thread(null, new Main(), "Main", 1 << 26).start();
    }

    static long gcd(long a, long b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

    static int gcd(int a, int b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

    static long modPow(long a, long p, long m) {
        if (a == 1) return 1;
        long ans = 1;
        while (p > 0) {
            if (p % 2 == 1) ans = (ans * a) % m;
            a = (a * a) % m;
            p >>= 1;
        }
        return ans;
    }

    static long modInv(long a, long m) {
        return modPow(a, m - 2, m);
    }

    static long sol_x, sol_y, gcd_a_b;

    static void extendedEuclid(long a, long b) {
        if (b == 0) {
            gcd_a_b = a;
            sol_x = 1;
            sol_y = 0;
        } else {
            extendedEuclid(b, a % b);
            long temp = sol_x;
            sol_x = sol_y;
            sol_y = temp - (a / b) * sol_y;
        }
    }

    long modInverse(long a, long prime)
    {
        a = a % prime;
        for (int x=1; x<prime; x++)
            if ((a*x) % prime == 1)
                return x;

        return -1;
    }

    static class Bhavansort {
        Random random;

        Bhavansort(int a[]) {
            randomArray(a);
            sort(a);
        }

        Bhavansort(long a[]) {
            randomArray(a);
            sort(a);
        }

        static int[] sort(int a[]) {
            Arrays.sort(a);
            return a;
        }

        static long[] sort(long a[]) {
            Arrays.sort(a);
            return a;
        }

        void randomArray(long a[]) {
            int n = a.length;
            for (int i = 0; i < n; i++) {
                int p = random.nextInt(n) % n;
                long tm = a[i];
                a[i] = a[p];
                a[p] = tm;
            }
        }

        void randomArray(int a[]) {
            int n = a.length;
            for (int i = 0; i < n; i++) {
                int p = random.nextInt(n) % n;
                int tm = a[i];
                a[i] = a[p];
                a[p] = tm;
            }
        }
    }


    int n,color[],ans[];
    Stack<Integer> temp[];
    ArrayList<Integer> l[];

    void dfs(int u,int par){
        ans[u]=temp[color[u]].peek();
        temp[color[u]].add(u);
        for(int v:l[u]){
            if(v==par)continue;
            dfs(v,u);
        }
        temp[color[u]].pop();
    }

    public void run() {
        InputReader sc = new InputReader(System.in);
        //Scanner sc=new Scanner(System.in);
        // Random rn=new Random();
        PrintWriter out = new PrintWriter(System.out);

        int n=sc.nextInt();
        int k=sc.nextInt();
        long a[]=new long[n];
        for (int i = 0; i <n ; i++) {
            if(i==0){
                a[i]=sc.nextInt();
            }
            else{
                a[i]=Math.min(a[i-1]*2,sc.nextInt());
            }
        }
        long ans=Long.MAX_VALUE,sum=0;
        for (int i = n-1; i >=0 ; i--) {
           // out.println(k+" "+i+" "+a[i]);
            long want=k/g(i);
            k-=want*g(i);
            sum+=want*a[i];
            ans=Math.min(ans,sum+(k>0?a[i]:0));
        }

        out.println(ans);

        out.close();
    }

    long g(int i){
        return (long)Math.pow(2,i);
    }
}
