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 java.util.*;
import java.io.*;
import java.math.BigInteger;
 
public class ProblemG
{
 
    static int mod = (int) (1e9+7);
    static InputReader in;
    static PrintWriter out;
    
    static void solve()
    {
        in = new InputReader(System.in);
        out = new PrintWriter(System.out);            
        
        int n = in.nextInt();
        int l = in.nextInt();
        long[] a = new long[33];
        long[] suf = new long[33];

        for(int i = 0; i < n; i++)
            a[i] = in.nextLong();
        
        for(int i = n; i < 33; i++){
            a[i] = a[i - 1] * 2l;
        }

        for(int i = 31; i >= 0; i--){
            a[i] = Math.min(a[i + 1], a[i]);
        }
        
        for(int i = 1; i < 33; i++){
            a[i] = Math.min(a[i - 1] * 2l, a[i]);
        }
        
        for(int i = 31; i >= 0; i--){
            a[i] = Math.min(a[i + 1], a[i]);
        }
        
        long c = 0;
        int i = 0;
        //debug(Integer.toBinaryString(l));
        
        while(l > 0){
            if(l % 2 != 0){
                c += a[i];
                c = Math.min(c, a[i + 1]);
            }
            l /= 2;
            i++;
        }
        
        //debug(i,a);
        c = Math.min(c, a[i]);
        
        out.println(c);
        out.close();
    }
    
    public static void main(String[] args)
    {
        new Thread(null ,new Runnable(){
            public void run(){
                try{
                    solve();
                } catch(Exception e){
                    e.printStackTrace();
                }
            }
        },"1",1<<26).start();
        
    }
 
    static class Pair implements Comparable<Pair>
    {
 
        long x,y;
 
        Pair (long x,long y)
        {
                this.x = x;
                this.y = y;
        }
        public int compareTo(Pair o)
        {
            return Long.compare(this.x,o.x);
                //return 0;
        }
 
        public boolean equals(Object o)
        {
            if (o instanceof Pair)
            {
                Pair p = (Pair)o;
                return p.x == x && p.y==y;
            }
            return false;
        }
 
        @Override
        public String toString()
        {
            return x + " "+ y ;
        }
 
        /*public int hashCode()
        {
            return new Long(x).hashCode() * 31 + new Long(y).hashCode();
        }*/
 
    } 
 
    static long add(long a,long b){
        long x=(a+b);
        while(x>=mod) x-=mod;
        return x;
    }
 
    static long sub(long a,long b){
        long x=(a-b);
        while(x<0) x+=mod;
        return x;
    }
    
    static long mul(long a,long b){
        long x=(a*b);
        while(x>=mod) x-=mod;
        return x;
    }
    
    static String rev(String s){
        StringBuilder sb=new StringBuilder(s);
        sb.reverse();
        return sb.toString();
    }
    
    static long gcd(long x,long y)
    {
        x = Math.abs(x);
        y = Math.abs(y);
        if(y==0)
                return x;
        else
                return gcd(y,x%y);
    }
 
    static int gcd(int x,int y)
    {
        x = Math.abs(x);
        y = Math.abs(y);
        if(y==0)
                return x;
        else 
                return gcd(y,x%y);
    }
 
    static long pow(long n,long p,long m)
    {
         long  result = 1;
          if(p==0){
            return 1;
          }
          
        while(p!=0)
        {
            if(p%2==1)
                result *= n;
            if(result >= m)
               result %= m;
            p >>=1;
            n*=n;
            if(n >= m)
                n%=m;
        }
        
        return result;
    }
 
    static long pow(long n,long p)
    {
        long  result = 1;
          if(p==0)
            return 1;
 
        while(p!=0)
        {
            if(p%2==1)
                result *= n;	    
            p >>=1;
            n*=n;	    
        }
        return result;
    }
 
    static void debug(Object... o)
    {
            System.out.println(Arrays.deepToString(o));
    }
 
    static class InputReader
    {
 
        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;
        private SpaceCharFilter filter;
 
        public InputReader(InputStream stream)
        {
                this.stream = stream;
        }
 
        public int snext()
        {
                if (snumChars == -1)
                        throw new InputMismatchException();
                if (curChar >= snumChars)
                {
                        curChar = 0;
                        try
                        {
                                snumChars = stream.read(buf);
                        } catch (IOException e)
                        {
                                throw new InputMismatchException();
                        }
                        if (snumChars <= 0)
                                return -1;
                }
                return buf[curChar++];
        }
 
        public int nextInt()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                int sgn = 1;
                if (c == '-')
                {
                        sgn = -1;
                        c = snext();
                }
                int res = 0;
                do
                {
                        if (c < '0' || c > '9')
                                throw new InputMismatchException();
                        res *= 10;
                        res += c - '0';
                        c = snext();
                } while (!isSpaceChar(c));
                return res * sgn;
        }
 
        public long nextLong()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                int sgn = 1;
                if (c == '-')
                {
                        sgn = -1;
                        c = snext();
                }
                long res = 0;
                do
                {
                        if (c < '0' || c > '9')
                                throw new InputMismatchException();
                        res *= 10;
                        res += c - '0';
                        c = snext();
                } while (!isSpaceChar(c));
                return res * sgn;
        }
 
        public int[] nextIntArray(int n)
        {
                int a[] = new int[n];
                for (int i = 0; i < n; i++)
                {
                        a[i] = nextInt();
                }
                return a;
        }
 
        public long[] nextLongArray(int n)
        {
                long a[] = new long[n];
                for (int i = 0; i < n; i++)
                {
                        a[i] = nextLong();
                }
                return a;
        }
 
        public String readString()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                StringBuilder res = new StringBuilder();
                do
                {
                        res.appendCodePoint(c);
                        c = snext();
                } while (!isSpaceChar(c));
                return res.toString();
        }
 
        public String nextLine()
        {
                int c = snext();
                while (isSpaceChar(c))
                        c = snext();
                StringBuilder res = new StringBuilder();
                do
                {
                        res.appendCodePoint(c);
                        c = snext();
                } while (!isEndOfLine(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;
        }
 
        private boolean isEndOfLine(int c)
        {
                return c == '\n' || c == '\r' || c == -1;
        }
 
        public interface SpaceCharFilter
        {
                public boolean isSpaceChar(int ch);
        }
 
    }
}    