101673: [AtCoder]ABC167 D - Teleporter
Description
Score: $400$ points
Problem Statement
The Kingdom of Takahashi has $N$ towns, numbered $1$ through $N$.
There is one teleporter in each town. The teleporter in Town $i$ $(1 \leq i \leq N)$ sends you to Town $A_i$.
Takahashi, the king, loves the positive integer $K$. The selfish king wonders what town he will be in if he starts at Town $1$ and uses a teleporter exactly $K$ times from there.
Help the king by writing a program that answers this question.
Constraints
- $2 \leq N \leq 2 \times 10^5$
- $1 \leq A_i \leq N$
- $1 \leq K \leq 10^{18}$
Input
Input is given from Standard Input in the following format:
$N$ $K$ $A_1$ $A_2$ $\dots$ $A_N$
Output
Print the integer representing the town the king will be in if he starts at Town $1$ and uses a teleporter exactly $K$ times from there.
Sample Input 1
4 5 3 2 4 1
Sample Output 1
4
If we start at Town $1$ and use the teleporter $5$ times, our travel will be as follows: $1 \to 3 \to 4 \to 1 \to 3 \to 4$.
Sample Input 2
6 727202214173249351 6 5 2 5 3 2
Sample Output 2
2