local mmi, mma = math.min, math.max local mfl, mce = math.floor, math.ceil local a, b, s = io.read("*n", "*n", "*n") local ret = 0LL for w = 1, s do local hlim = mfl(s / w) if w <= a then local x = a - w + 1LL local ymin = mma(1, b - hlim + 1) local ymax = b local ysum = (ymax - ymin + 1LL) * (ymin + ymax) / 2LL ret = ret + ysum * x end end ret = tostring(ret):gsub("LL", "") print(ret)