i, k, s = map(int, raw_input().strip().split())
a, b = map(int, raw_input().strip().split())

from math import sqrt
sqrt2 = sqrt(2)
sqrt6 = sqrt(6)
if (i ^ k) & 1:
    i += 1
    a, b = (
        sqrt2 * (a + b) - sqrt6 * (a - b),
        sqrt2 * (a - b) + sqrt6 * (a + b),
    )

ans = (a + b) * pow(0.5, s + 2*(i - k))
print "%.11lf" % ans