Buggy python submission (verdict: Runtime Error):
import sys
import os
import math
import bisect
import collections
import itertools
import heapq

ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]

iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]

lcm = lambda x, y: x * y / math.gcd(x, y)

MOD = 10 ** 9 + 7
MAX = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    N, K = il()
    A = il()
    t = [0]*N
    tmp = 1
    cnt = 0
    for n in range(N):
        if t[tmp-1] != 0:
            break
        cnt += 1
        t[n] = tmp
        tmp = A[tmp - 1]
    else:
        print(t[cnt-1])
        exit()

    mod = (K - cnt) % (len(t)-cnt)
    print(t[len(t)-cnt+1:][mod])


if __name__ == '__main__':
    main()


Fixed submission:
import sys
import os
import math
import bisect
import collections
import itertools
import heapq
import re
import queue
from decimal import Decimal

# import fractions

sys.setrecursionlimit(10000000)

ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]

iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]

lcm = lambda x, y: (x * y) // math.gcd(x, y)
# lcm = lambda x, y: (x * y) // fractions.gcd(x, y)

MOD = 10 ** 9 + 7
MAX = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    N, K = il()
    tel = [0] + il()

    # 初期位置
    position = 1

    # 移動回数がN回(町の数)以下の場合
    if K <= N:
        for k in range(K):
            position = tel[position]
        print(position)
        exit()

    # 移動回数がN回(町の数)以上の場合
    for n in range(N):
        position = tel[position]

    # 既にN回移動済みのため、
    # 必要な移動回数(K)から減算
    K -= N
    # ループまでに必要な移動回数を探索
    base = position
    cnt = 1
    while base != tel[position]:
        position = tel[position]
        cnt += 1

    # Kからループ数の余りを求め、
    # 余りの回数だけ移動を行う
    for k in range(K % cnt + 1):
        position = tel[position]
    print(position)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
import sys
import os
import math
import bisect
import collections
import itertools
import heapq

ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]

iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]

lcm = lambda x, y: x * y / math.gcd(x, y)

MOD = 10 ** 9 + 7
MAX = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    N, K = il()
    A = il()
    t = [0]*N
    tmp = 1
    cnt = 0
    for n in range(N):
        if t[tmp-1] == 0:
            t[tmp-1] = A[tmp-1]
            tmp = A[tmp-1]
            cnt += 1
        else:
            break
    else:
        print(t[cnt-1])
        exit()

    mod = (K - cnt) % (len(t)-cnt)
    print(t[len(t)-cnt+1:][mod])


if __name__ == '__main__':
    main()


Fixed submission:
import sys
import os
import math
import bisect
import collections
import itertools
import heapq
import re
import queue
from decimal import Decimal

# import fractions

sys.setrecursionlimit(10000000)

ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]

iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]

lcm = lambda x, y: (x * y) // math.gcd(x, y)
# lcm = lambda x, y: (x * y) // fractions.gcd(x, y)

MOD = 10 ** 9 + 7
MAX = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    N, K = il()
    tel = [0] + il()

    # 初期位置
    position = 1

    # 移動回数がN回(町の数)以下の場合
    if K <= N:
        for k in range(K):
            position = tel[position]
        print(position)
        exit()

    # 移動回数がN回(町の数)以上の場合
    for n in range(N):
        position = tel[position]

    # 既にN回移動済みのため、
    # 必要な移動回数(K)から減算
    K -= N
    # ループまでに必要な移動回数を探索
    base = position
    cnt = 1
    while base != tel[position]:
        position = tel[position]
        cnt += 1

    # Kからループ数の余りを求め、
    # 余りの回数だけ移動を行う
    for k in range(K % cnt + 1):
        position = tel[position]
    print(position)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
import sys
import os
import math
import bisect
import collections
import itertools
import heapq

ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]

iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]

lcm = lambda x, y: x * y / math.gcd(x, y)

MOD = 10 ** 9 + 7
MAX = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    N, K = il()
    A = il()
    t = [0]*N
    tmp = 1
    cnt = 0
    for n in range(N):
        if tmp in t:
            break
        cnt += 1
        t[n] = tmp
        tmp = A[tmp - 1]
    else:
        print(t[cnt-1])
        exit()

    mod = (K - cnt) % (len(t)-cnt)
    print(t[len(t)-cnt+1:][mod])


if __name__ == '__main__':
    main()


Fixed submission:
import sys
import os
import math
import bisect
import collections
import itertools
import heapq
import re
import queue
from decimal import Decimal

# import fractions

sys.setrecursionlimit(10000000)

ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]

iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]

lcm = lambda x, y: (x * y) // math.gcd(x, y)
# lcm = lambda x, y: (x * y) // fractions.gcd(x, y)

MOD = 10 ** 9 + 7
MAX = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    N, K = il()
    tel = [0] + il()

    # 初期位置
    position = 1

    # 移動回数がN回(町の数)以下の場合
    if K <= N:
        for k in range(K):
            position = tel[position]
        print(position)
        exit()

    # 移動回数がN回(町の数)以上の場合
    for n in range(N):
        position = tel[position]

    # 既にN回移動済みのため、
    # 必要な移動回数(K)から減算
    K -= N
    # ループまでに必要な移動回数を探索
    base = position
    cnt = 1
    while base != tel[position]:
        position = tel[position]
        cnt += 1

    # Kからループ数の余りを求め、
    # 余りの回数だけ移動を行う
    for k in range(K % cnt + 1):
        position = tel[position]
    print(position)


if __name__ == '__main__':
    main()