loop do
  n, m, pct = gets.chomp.split.map(&:to_i)
  break if n + m + pct == 0
  x = []
  
  n.times do
    x << gets.to_i
  end
  
  puts x[m - 1] == 0 ? 0 : x.inject(&:+) * 100 * (100 - pct) / 100 / x[m - 1]
end