SmallR is an archer. SmallR is taking a match of archer with Zanoes. They try to shoot in the target in turns, and SmallR shoots first. The probability of shooting the target each time is <img align="middle" class="tex-formula" src="https://espresso.codeforces.com/a7487d7e62f90136b78ae3fbf0a008396f146e13.png" style="max-width: 100.0%;max-height: 100.0%;"/> for SmallR while <img align="middle" class="tex-formula" src="https://espresso.codeforces.com/c443c7703e51f03d0eece0b96b9e84e425878209.png" style="max-width: 100.0%;max-height: 100.0%;"/> for Zanoes. The one who shoots in the target first should be the winner.

Output the probability that SmallR will win the match.
A single line contains four integers <img align="middle" class="tex-formula" src="https://espresso.codeforces.com/488158367221f441ba94b9475c03436069df2a7e.png" style="max-width: 100.0%;max-height: 100.0%;"/>.


a, b, c, d = map(int, input().split())

print((a/b) / (1 - (1-a/b)*(1-c/d)))


# a = [0] * 7
# def check_possibility(s, drop_count):
#     if s < 7:
#         a[s] += 1 / drop_count
#
# total = 0
# for a1 in range(1, 7):
#     check_possibility(a1, 6)
#     for a2 in range(1, 7):
#         check_possibility(a1 + a2, 6**2)
#         for a3 in range(1, 7):
#             check_possibility(a1 + a2 + a3, 6**3)
#             for a4 in range(1, 7):
#                 check_possibility(a1 + a2 + a3 + a4, 6**4)
#                 for a5 in range(1, 7):
#                     check_possibility(a1 + a2 + a3 + a4 + a5, 6**5)
#                     for a6 in range(1, 7):
#                         check_possibility(a1 + a2 + a3 + a4 + a5 + a6, 6**6)
#
# print(a)
# r = 0
# print(sum(a) / 6)
#
# print(total)
