N, S, K = gets.split.map(&:to_i)
A = N.times.map { gets.to_i }

best_idx = -1
min_diff = K + 1

A.each.with_index(1) do |a, i|
  diff = (a - S).abs

  if min_diff > diff
    min_diff = diff
    best_idx = i
  end
end

if best_idx == -1
  puts 'Unlucky!'
else
  puts best_idx
end