P17496 [ICPC 2026 Wuhan I] Prime Game

Iroha and Kaguya have recently become fascinated by a mathematical game based on integers. Initially, they share a positive integer $n$. The two players take turns performing operations; a single round is defined as both Iroha and Kaguya completing one operation each. In each round: 1. Iroha goes first: She must choose a non-negative integer $x$ ($0 \le x

The first line contains an integer $n$ ($1 \le n \le 10^{18}$), representing the initial number of the game.

Output a single line containing an integer, representing the total number of rounds the game will last given that both players play optimally.