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.*;
 
public class Main {
    public static void main(String[] args) throws IOException {
        PrintWriter out = new PrintWriter(System.out);
        //Scanner sc = new Scanner();
        Reader in = new Reader();
        Main solver = new Main();
        solver.solve(out, in);
        out.flush();
        out.close();
 
    }
 
    static long INF = (long)1e18;
    static int maxn = (int)1e5+100;
    static int mod= 998244353 ;
    static int n,m,k,t,q,d;
    
    
    void solve(PrintWriter out, Reader in) throws IOException{
        n = in.nextInt();
        int lit = in.nextInt();
        
        int[] pwr = new int[n+1];
        pwr[1]=1;
        for(int i=2;i<=n;i++) pwr[i] = pwr[i-1]*2;
        int[] cost = new int[n+1];
        for(int i=1;i<=n;i++) cost[i] = in.nextInt();
        
        for(int i=1;i<n;i++){
            if(cost[i]*2<cost[i+1]){
                cost[i+1] = cost[i]*2;
            }
        }
        
        long ans = 0,res=INF;
        
        for(int i=n;i>=1;i--){
            if(pwr[i]>lit) res = Math.min(res,ans+cost[i]);
            while(pwr[i]<=lit){
                int x = lit/pwr[i];
                ans+=(long)cost[i]*(long)x;
                lit-=x*pwr[i];
                
                if(lit<pwr[i]) res = Math.min(res,ans+cost[i]);
            }
        }
        res = Math.min(res,ans);
        out.println(res);
    }
    
    
    static class Reader {

    private InputStream mIs;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;

    public Reader() {
        this(System.in);
    }

    public Reader(InputStream is) {
        mIs = is;
    }

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

    }
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = mIs.read(buf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (numChars <= 0) {
                return -1;
            }
        }
        return buf[curChar++];
    }

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

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

    double nextDouble()
    {
        return Double.parseDouble(next());
    }

    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 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 boolean isSpaceChar(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public boolean isEndOfLine(int c) {
        return c == '\n' || c == '\r' || c == -1;
    }

    }
}