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.
/* Author: Ronak Agarwal */
import java.io.* ; import java.util.* ; import java.math.* ;
import static java.lang.Math.min ;
import static java.lang.Math.max ;
import static java.lang.Math.abs ;
/* Thread is created here to increase the stack size of the java code so that recursive dfs can be performed */
public class Codeshefcode{
	public static void main(String[] args) throws IOException{
		new Thread(null,new Runnable(){	public void run(){ exec_Code() ;} },"Solver",1l<<27).start() ;
	}
	static void exec_Code(){
		try{
			Solver Machine = new Solver() ;
			Machine.Solve() ; Machine.Finish() ;}
		catch(Exception e){ e.printStackTrace() ; print_and_exit() ;}
		catch(Error e){ e.printStackTrace() ; print_and_exit() ; }
	}
	static void print_and_exit(){ System.out.flush() ; System.exit(-1) ;}
}
class Reader{
	BufferedReader reader;
	StringTokenizer tkz;
	Reader(InputStream input) {
		reader = new BufferedReader(new InputStreamReader(input)) ;
		tkz = new StringTokenizer("") ;
	}
	String s() throws IOException{
		while (!tkz.hasMoreTokens()) tkz = new StringTokenizer(reader.readLine()) ;
		return tkz.nextToken() ;
	}
	int i() throws IOException{ return Integer.parseInt(s()) ;}
	long l() throws IOException{ return Long.parseLong(s()) ;}
	double d() throws IOException{	return Double.parseDouble(s()) ;}
}
/* All the useful functions,constants,renamings are here*/
class Template{
	/* Constants Section */
	final int INT_MIN = Integer.MIN_VALUE ; final int INT_MAX = Integer.MAX_VALUE ;
	final long LONG_MIN = Long.MIN_VALUE ; final long LONG_MAX = Long.MAX_VALUE ;
	static long MOD = 1000000007 ;
	static Reader ip = new Reader(System.in) ;	
	static PrintWriter op = new PrintWriter(System.out) ;
	/* Methods for writing */
	static void p(Object o){ op.print(o) ; }
	static void pln(Object o){ op.println(o) ;}
	static void Finish(){ op.flush();	op.close(); }
	/* Implementation of operations modulo MOD */
	static long inv(long a){ return powM(a,MOD-2) ; }
	static long m(long a,long b){ return (a*b)%MOD ; }
	static long d(long a,long b){ return (a*inv(b))%MOD ; }
	static long powM(long a,long b){
		if(b<0) return powM(inv(a),-b) ;
		long val=a ; long ans=1 ;
		while(b!=0){
			if((b&1)==1) ans = (ans*val)%MOD ; 
			val = (val*val)%MOD ; 
			b/=2 ;
		}
		return ans ;
	}
	/* Renaming of some generic utility classes */
	final static class mylist extends ArrayList<Integer>{}
	final static class myset extends TreeSet<pair>{}
	final static class mystack extends Stack<Integer>{}
	final static class mymap extends TreeMap<Long,Integer>{}
}
/* Implementation of the pair class, useful for every other problem */
class pair implements Comparable<pair>{
	double x ; long y ;
	pair(double _x,long _y){ x=_x ; y=_y ;} 
	public int compareTo(pair p){
		return (this.x<p.x ? -1 : (this.x>p.x ? 1 : (this.y<p.y ? -1 : (this.y>p.y ? 1 : 0)))) ;
	}
}
/* Main code starts here */
class Solver extends Template{
	int n,mpos[] ;
	long c[] ;
	double rat[] ;
	long cost(int lim,long L){
		if(lim==1)
			return c[lim]*L ;
		long cap = 1l<<(lim-1) ;
		long res = c[lim]*(L/cap) ;
		L%=cap ;
		if(L==0) return res ;
		long poss1 = c[lim] ;
		long poss2 = cost(mpos[lim-1],L) ;
		return res+min(poss1,poss2) ;
	}
	public void Solve() throws IOException{
		n = ip.i() ;
		long L = ip.l() ;
		c = new long[n+1] ;
		rat = new double[n+1] ;
		for(int i=1 ; i<=n ; i++) c[i] = ip.i() ;
		for(int i=1 ; i<=n ; i++) rat[i] = c[i]/((1l<<(i-1))+0.0) ;
		mpos = new int[n+2] ;
		double mnval = Double.POSITIVE_INFINITY ;
		for(int i=1 ; i<=n ; i++){
			if(rat[i]<mnval){
				mnval=rat[i] ;
				mpos[i]=i ;
			}else
				mpos[i]=mpos[i-1] ;
		}
		mpos[n+1] = mpos[n] ;
		pln(cost(mpos[n+1],L)) ;
	}
}