EPS = 1.0e-8

r, d = map(float, input().split())

ng = 0
ok = 1.0e5
while abs(ok - ng) > EPS:
  mid = (ok + ng) / 2
  if mid * mid >= d ** 2 - r ** 2:
    ok = mid
  else:
    ng = mid

print("{:.7f}".format(ok))