import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, 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 LIM = 1000;

void main() {
  try {
    for (; ; ) {
      const A = abs(readLong());
      const B = abs(readLong());
      
      const d = gcd(A, B);
      real[] summands;
      if (d == 0) {
        summands ~= pow(2.0L, -2.0L);
      } else {
        const odd = (A / d % 2 != 0 && B / d % 2 != 0);
        foreach (i; 0 .. LIM / d + 1) {
          if (odd && i % 2 != 0) {
            continue;
          }
          const real r = 2 + d * i;
          debug {
            writeln(i, " ", r);
          }
          summands ~= (i + 1) * pow(r, -r);
        }
      }
      
      const ans = summands.sum;
      writefln("%.12f", ans);
    }
  } catch (EOFException e) {
  }
}