a,b,t = STDIN.read.chomp.split(" ")

tot_time = t.to_f + 0.5
time_apan = a.to_f
buisquets_per_span = b.to_i

counter = 1
tot_buisquets = 0
time_passed = 0
while time_apan < tot_time
  tot_buisquets += buisquets_per_span
  counter += 1
  time_passed += time_apan
  time_apan = time_apan * counter
end
puts tot_buisquets
