#!/usr/bin/env python3

n, m = [int(i) for i in input().split()]
xs = [int(i) for i in input().split()]
# local minimum is whenever s(f) jumps or at f=M

# first do f = M
optt = 0
for x in xs:
    if (m * x) % 1000 == 0:
        optt += (m * x) // 1000
    else:
        optt += 1 + (m * x) // 1000
optt /= m

# now all other interesting points
fs = {}
for x in xs:
    maxv = (m * x) // 1000
    for i in range(1, maxv + 1):
        f = (i * 1000) / x
        if not f in fs:
            fs[f] = 1
        else:
            fs[f] += 1

# enumerate in sorted order
# with arbitrary low framerate each level takes 1 frame
sf = n
for f in sorted(fs):
    t = sf / f
    if t < optt:
        optt = t
    sf += fs[f]
print(optt)

# note: it does not really matter if we correctly group all of the same f
# into the same group (perhaps due to rounding errors), as only incrementing
# the number of frames while increasing the framerate negligibly will not
# lead to a more optimal answer.