Problem:
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

Solution in Go (1.14.1) (judge verdict: Runtime Error)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func scanInt() int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return i
}

func scanInt64() int64 {
	sc.Scan()
	i, _ := strconv.ParseInt(sc.Text(), 10, 64)
	return i
}

func scanInts(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = scanInt()
	}
	return res
}

func scanInts64(n int) []int64 {
	res := make([]int64, n)
	for i := range res {
		res[i] = scanInt64()
	}
	return res
}

var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Split(bufio.ScanWords)

	n, k := scanInt(), scanInt()
	a := make([]int, n)
	for i := range a {
		a[i] = scanInt() - 1
	}
	fg := []int{a[0]}
	for i := 0; i < n+100; i++ {
		fg = append(fg, a[fg[len(fg)-1]])
	}

	if k <= n {
		fmt.Println(fg[k-1])
	}

	loopEnd := n - 1
	loopStart := n - 2
	loopLen := 0
	for i := 0; i < n; i++ {
		if fg[loopEnd] == fg[loopStart] {
			loopLen = loopEnd - loopStart
			break
		}
		loopStart--
	}

	k %= loopLen
	if k < n {
		k += loopLen
	}

	fmt.Println(fg[k-1] + 1)
}