import java.io.BufferedReader import java.io.InputStream import java.io.InputStreamReader import java.io.PrintWriter import java.lang.StringBuilder import java.util.* fun PrintWriter.solve(sc: FastScanner) { val n = sc.nextInt() val k = sc.nextInt() var ans = 0 val mod = 1000000007 val stack = Stack() stack.add(0) while (stack.count() > 0) { val m = stack.pop() ans++ if (ans >= mod) ans -= mod for (i in m + k..n) { stack.add(i) } } println(ans) } fun main(args: Array) { val writer = PrintWriter(System.out, false) writer.solve(FastScanner(System.`in`)) writer.flush() } class FastScanner(s: InputStream) { private var st = StringTokenizer("") private val br = BufferedReader(InputStreamReader(s)) fun next(): String { while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine()) return st.nextToken() } fun nextInt() = next().toInt() fun nextLong() = next().toLong() fun nextLine() = br.readLine() fun nextDouble() = next().toDouble() fun ready() = br.ready() }