8.THE NECKLACE QUESTION
Credits: 300
PROBLEM DESCRIPTION:
Consider a necklace made of 2N-1 black and white beads, K of which are black. Necklace is called "beautiful" if it is possible to choose two black beads (not necessarily different) in such a way that one of two necklace parts strictly between them contains exactly N beads.
For example, if N=4 and K=3, necklace "WBWBWBW" is beautiful, and necklace "BBWWBWW" is not.
You need to find minimal K for which every necklace of 2N-1 beads is beatiful.
INPUT:
The first line of input contains odd integer number 2N-1 (5<=2N-1<=2^31-1).
OUTPUT:
Output minimal K for which every necklace of 2N-1 beads is beatiful.
SAMPLE INPUT:
Test #1
5
Test #2
7
SAMPLE OUTPUT:
Test #1
3
Test #2
4