A, B, C = gets.split.map(&:to_i)

ok = 10 ** 18
ng = 0

def f(x)
  b = x / A
  a = x - b

  B * b + a >= C
end

while (ok - ng).abs >= 2
  x = (ok + ng) / 2

  if f(x)
    ok = x
  else
    ng = x
  end
end

puts ok