The overall program length can be expressed as U+log2(n0), where U is some constant and log2(n0) represents the length of the integer value n0, under the reasonable assumption that it is encoded in binary digits. Now consider the function f:[2,∞)→[1,∞), defined by f(x) = x − log2(x). It is strictly increasing on its domain, and hence has an inverse f−1:[1,∞)→[2,∞).