import std.conv, std.functional, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum N = 101;

int P0, Q;

void main() {
  try {
    for (; ; ) {
      P0 = readInt();
      Q = readInt();
      
      /*
        x[i] = (i/100) (1/2 + (1/2) x[i-Q]) + (1 - i/100) (1/3 + (1/3) x[i+Q])
      */
      auto a = new real[][](N, N + 1);
      foreach (i; 0 .. N) {
        const p = i / 100.0L;
        a[i][] = 0.0;
        a[i][i] += 1.0;
        a[i][max(i - Q, 0)] -= p / 2.0;
        a[i][min(i + Q, N - 1)] -= (1.0 - p) / 3.0;
        a[i][N] += p / 2.0 + (1.0 - p) / 3.0;
      }
      
      foreach (h; 0 .. N) {
        foreach (i; h + 1 .. N) {
          if (abs(a[h][h]) < abs(a[i][h])) {
            swap(a[h], a[i]);
          }
        }
        assert(abs(a[h][h]) > 1e-10);
        foreach (j; h + 1 .. N + 1) {
          a[h][j] /= a[h][h];
        }
        a[h][h] = 1.0;
        foreach (i; h + 1 .. N) {
          foreach (j; h + 1 .. N + 1) {
            a[i][j] -= a[i][h] * a[h][j];
          }
          a[i][h] = 0.0;
        }
      }
      foreach_reverse (i; 0 .. N) {
        foreach (j; i + 1 .. N) {
          a[i][N] -= a[i][j] * a[j][N];
        }
      }
      
      real ans = 0.0;
      ans += 1.0L / 3.0;
      ans += 1.0L / 3.0 * a[P0][N];
      writefln("%.10f", ans);
    }
  } catch (EOFException e) {
  }
}