a, b, k = gets.chomp.split(" ").map(&:to_i)
INF = Float::INFINITY
left = -1
right = 10**18
lcm = a.lcm(b)
while right - left > 1
    mid = (left + right) / 2
    point = mid+1
    ans = (point / a) + (point / b) - (point/lcm)
    if ans >= k
        right = mid
    else
        left = mid
    end
end
puts right + 1