local n, s, k = io.read("*n", "*n", "*n")
local cand, diff = -1, 0
for i = 1, n do
  local a = io.read("*n")
  local d = math.abs(a - s)
  if d <= k then
    if cand < 0 or d < diff then
      cand, diff = i, d
    end
  end
end
if 0 < cand then
  print(cand)
else
  print("Unlucky!")
end