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

public class CODEFORCES
{
	@SuppressWarnings("rawtypes")
	static InputReader in;
	static PrintWriter out;

	static void solve()
	{
		int n = in.ni();
		long l = in.ni();
		long arr[] = new long[n];
		for (int i = 0; i < n; i++)
		{
			arr[i] = in.ni();
			long t = 2;
			for (int j = i - 1; j >= 0; j--)
			{
				arr[i] = Math.min(arr[i], t * arr[j]);
				t <<= 1;
			}
		}
		long ans = 0, ans1 = Long.MAX_VALUE;
		long tmp = l;
		for (int i = n - 1; i >= 0; i--)
		{
			long j = 1 << i;
			long keep = l / j;
			long ke = (long) Math.ceil(l / (double) j);
			ans1 = Math.min(ans1, ans + ke * arr[i]);
			ans += arr[i] * keep;
			l -= keep * j;
		}
		ans = Math.min(ans1, ans1);
		// debug(ans);
		for (int i = n - 1; i >= 0; i--)
		{
			long j = 1 << i;
			long keep = (long) Math.ceil(tmp / (double) j);
			ans = Math.min(ans, keep * arr[i]);
		}
		out.println(ans);
	}

	@SuppressWarnings("rawtypes")
	static void soln()
	{
		in = new InputReader(System.in);
		out = new PrintWriter(System.out);
		solve();
		out.flush();
	}

	static void debug(Object... o)
	{
		System.out.println(Arrays.deepToString(o));
	}

	public static void main(String[] args)
	{
		new Thread(null, new Runnable()
		{
			public void run()
			{
				try
				{
					soln();
				} catch (Exception e)
				{
					e.printStackTrace();
				}
			}
		}, "1", 1 << 26).start();
	}

	// To Get Input
	// Some Buffer Methods
	static class InputReader<SpaceCharFilter>
	{

		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 ni()
		{
			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 nl()
		{
			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] = ni();
			}
			return a;
		}

		public long[] nextLongArray(int n)
		{
			long a[] = new long[n];
			for (int i = 0; i < n; i++)
			{
				a[i] = nl();
			}
			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);
		}

	}
}