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.*;
 public class Solution {
		static FastScanner scr=new FastScanner();
//		static Scanner scr=new Scanner(System.in);
		static PrintStream out=new PrintStream(System.out);
		static StringBuilder sb=new StringBuilder();
		
		
		
		
		static class pair{
			int x;int y;
			pair(int x,int y){ 
				this.x=x;this.y=y;
				
			}
		}
		static class triplet{
			int x;
			long y;
			int z;
			triplet(int x,long y,int z){
				this.x=x;
				this.y=y;
				this.z=z;
			}
		}
		static class FastScanner {
			 BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
			StringTokenizer st=new StringTokenizer("");
		 	String next() {
		 		while (!st.hasMoreTokens())
		 			try {
		 				st=new StringTokenizer(br.readLine());
		 			} catch (IOException e) {
		 				e.printStackTrace();
		 			}
		 			return st.nextToken();
			} long gcd(long a,long b){
				if(b==0) {
					return a;
				}
					
				return gcd(b,a%b);
			}
		 	int[]  sort(int a[]) {
				 
		        int multiplier = 1, len = a.length, max = Integer.MIN_VALUE;
		        int b[] = new int[len];
		        int bucket[];
		        for (int i = 0; i < len; i++) if (max < a[i]) max = a[i];
		        while (max / multiplier > 0) {
		            bucket = new int[10];
		            for (int i = 0; i < len; i++) bucket[(a[i] / multiplier) % 10]++;
		            for (int i = 1; i < 10; i++) bucket[i] += (bucket[i - 1]);
		            for (int i = len - 1; i >= 0; i--) b[--bucket[(a[i] / multiplier) % 10]] = a[i];
		            for (int i = 0; i < len; i++) a[i] = b[i];
		            multiplier *= 10;
		        }
		        return a;
		    }
		 	 long modPow(long base,long exp) {
				if(exp==0) {
					return 1;
				}
				if(exp%2==0) {
					long res=(modPow(base,exp/2));
					return (res*res);
				}
				return (base*modPow(base,exp-1));
			}
			int []reverse(int a[]){
				int b[]=new int[a.length];
				int index=0;
				for(int i=a.length-1;i>=0;i--) {
					b[index]=a[i];
				}
				return b;
			}
			int nextInt() {
				return Integer.parseInt(next());
			}
			int[] readArray(int n) {
				int[] a=new int[n];
				for (int i=0; i<n; i++) a[i]=nextInt();
				return a;
			}
			long[] readLongArray(int n) {
				long  [] a=new long  [n];
				for (int i=0; i<n; i++) a[i]=nextLong();
				return a;
			}
			long nextLong() {
				return Long.parseLong(next());
			}
		}
		
		static int prime[];
		static void solve() {
			int n = scr.nextInt();
			int l=scr.nextInt();
			int []a=scr.readArray(n);
			for(int i=1;i<n;i++) {
				a[i]=Math.min(a[i],a[i-1]*2);
			}
			
			long totalCost=Long.MAX_VALUE;
			long sum=0;
			for(int i=n-1;i>=0;i--) {
				int div=(l)/(1<<i);
				sum+=div*(long)a[i];
				l=(l%(1<<i));
				if(l==0) {
					totalCost=Math.min(totalCost,sum);
				}else {
					totalCost=Math.min(totalCost, sum+a[i]);
				}
			}
			out.println(totalCost);
		}	
		static int  MAX = Integer.MAX_VALUE;
		static int  MIN = Integer.MIN_VALUE;
		public static void main(String []args) {
//			int t=scr.nextInt();
//			while(t-->0) {
//				solve();
//			}
			solve();
			out.println(sb);
		}
	}
 	