import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.io.BufferedWriter;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;
/**
* Built using CHelper plug-in
* Actual solution is at the top
*
* @author Egor Kulikov (egor@egork.net)
*/
public class Main {
public static void main(String[] args) {
InputStream inputStream = System.in;
OutputStream outputStream = System.out;
InputReader in = new InputReader(inputStream);
OutputWriter out = new OutputWriter(outputStream);
TaskF solver = new TaskF();
solver.solve(1, in, out);
out.close();
}
static class TaskF {
long[][] answer;
long[][] sum;
int base;
public void solve(int testNumber, InputReader in, OutputWriter out) {
int n = in.readInt();
int k = in.readInt();
base = n - k + 1;
answer = new long[n + 1][n + 1];
sum = new long[n + 1][n + 1];
ArrayUtils.fill(answer, -1);
ArrayUtils.fill(sum, -1);
long answer = go(n, n) * IntegerUtils.power(2, Math.max(n - k - 1, 0), MiscUtils.MOD7) % MiscUtils.MOD7;
out.printLine(answer);
}
private long go(int n, int lim) {
lim = Math.min(lim, n);
if (answer[n][lim] != -1) {
return answer[n][lim];
}
if (n == base) {
return answer[n][lim] = 1;
}
return answer[n][lim] = (go(n - 1, lim) + goSum(n - 1, lim - 1)) % MiscUtils.MOD7;
}
private long goSum(int n, int lim) {
if (sum[n][lim] != -1) {
return sum[n][lim];
}
if (lim <= 1) {
return sum[n][lim] = 0;
}
return sum[n][lim] = (go(n, lim) + goSum(n, lim - 1)) % MiscUtils.MOD7;
}
}
static class ArrayUtils {
public static void fill(long[][] array, long value) {
for (long[] row : array) {
Arrays.fill(row, value);
}
}
}
static class InputReader {
private InputStream stream;
private byte[] buf = new byte[1024];
private int curChar;
private int numChars;
private InputReader.SpaceCharFilter filter;
public InputReader(InputStream stream) {
this.stream = stream;
}
public int read() {
if (numChars == -1) {
throw new InputMismatchException();
}
if (curChar >= numChars) {
curChar = 0;
try {
numChars = stream.read(buf);
} catch (IOException e) {
throw new InputMismatchException();
}
if (numChars <= 0) {
return -1;
}
}
return buf[curChar++];
}
public int readInt() {
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) {
if (filter != null) {
return filter.isSpaceChar(c);
}
return isWhitespace(c);
}
public static boolean isWhitespace(int c) {
return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
}
public interface SpaceCharFilter {
public boolean isSpaceChar(int ch);
}
}
static class OutputWriter {
private final PrintWriter writer;
public OutputWriter(OutputStream outputStream) {
writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
}
public OutputWriter(Writer writer) {
this.writer = new PrintWriter(writer);
}
public void close() {
writer.close();
}
public void printLine(long i) {
writer.println(i);
}
}
static class IntegerUtils {
public static long power(long base, long exponent, long mod) {
if (base >= mod) {
base %= mod;
}
if (exponent == 0) {
return 1 % mod;
}
long result = power(base, exponent >> 1, mod);
result = result * result % mod;
if ((exponent & 1) != 0) {
result = result * base % mod;
}
return result;
}
}
static class MiscUtils {
public static final int MOD7 = (int) (1e9 + 7);
}
}