Buggy python submission (verdict: Runtime Error):
from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from fractions import gcd
from itertools import combinations # (string,3) 3回
from collections import deque
from collections import defaultdict
import bisect
#
#    d = m - k[i] - k[j]
#    if kk[bisect.bisect_right(kk,d) - 1] == d:
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#

import sys
sys.setrecursionlimit(10000000)
mod = 10**9 + 7

def readInts():
  return list(map(int,input().split()))
def main():
    n,k = readInts()
    A = readInts()
    root = []
    ok = True
    l = 0
    while True:
        if ok:
            a = 1
            ok = False
        else:
            a = root[-1]
        if not A[a-1] in root:
            root.append(A[a-1])
        else:
            j = 0
            for i in range(len(root)):
                if A[a-1] == root[i]:
                    j = i
                    break
            root = root[j:]
            l = j
            #print(root)
            break

    #print(root)
    print(root[k%len(root) - (l+1)])
if __name__ == '__main__':
  main()


Fixed submission:
from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from fractions import gcd
from itertools import combinations # (string,3) 3回
from collections import deque
from collections import defaultdict
import bisect
#
#    d = m - k[i] - k[j]
#    if kk[bisect.bisect_right(kk,d) - 1] == d:
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#

import sys
sys.setrecursionlimit(10000000)
mod = 10**9 + 7

def readInts():
  return list(map(int,input().split()))
def main():
    n,k = readInts()
    A = readInts()
    root = []
    ok = True
    l = 0
    start = [1]
    dic = defaultdict(int)
    while True:
        if ok:
            a = 1
            ok = False
        else:
            a = root[-1]
        if not dic[A[a-1]]:
            dic[A[a-1]] = a
            root.append(A[a-1])
        else:
            j = 0
            for i in range(len(root)):
                if A[a-1] == root[i]:
                    j = i
                    break
                start.append(root[i])
            root = root[j:]
            l = j
            break
    if k < len(start):
        print(start[k])
    else:
        k = k - (l+1) if k - (l+1) >= 0 else k
        print(root[k%len(root)])
if __name__ == '__main__':
  main()

Buggy python submission (verdict: Runtime Error):
from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from fractions import gcd
from itertools import combinations # (string,3) 3回
from collections import deque
from collections import defaultdict
import bisect
#
#    d = m - k[i] - k[j]
#    if kk[bisect.bisect_right(kk,d) - 1] == d:
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#

import sys
sys.setrecursionlimit(10000000)
mod = 10**9 + 7

def readInts():
  return list(map(int,input().split()))
def main():
    n,k = readInts()
    A = readInts()
    root = []
    ok = True
    l = 0
    while True:
        if ok:
            a = 1
            ok = False
        else:
            a = root[-1]
        if not A[a-1] in root:
            root.append(A[a-1])
        else:
            j = 0
            for i in range(len(root)):
                if A[a-1] == root[i]:
                    j = i
                    break
            root = root[j:]
            l = j
            #print(root)
            break

    #print(root)
    print(root[k%len(root) - (l+1)])
if __name__ == '__main__':
  main()


Fixed submission:
from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from fractions import gcd
from itertools import combinations # (string,3) 3回
from collections import deque
from collections import defaultdict
import bisect
#
#    d = m - k[i] - k[j]
#    if kk[bisect.bisect_right(kk,d) - 1] == d:
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#

import sys
sys.setrecursionlimit(10000000)
mod = 10**9 + 7

def readInts():
  return list(map(int,input().split()))
def main():
    n,k = readInts()
    A = readInts()
    root = []
    ok = True
    l = 0
    start = [1]
    dic = defaultdict(int)
    while True:
        if ok:
            a = 1
            ok = False
        else:
            a = root[-1]
        if not dic[A[a-1]]:
            dic[A[a-1]] = a
            root.append(A[a-1])
        else:
            j = 0
            for i in range(len(root)):
                if A[a-1] == root[i]:
                    j = i
                    break
                start.append(root[i])
            root = root[j:]
            l = j
            break
    if k < len(start):
        print(start[k])
    else:
        k = k - (l+1) if k - (l+1) >= 0 else k
        print(root[k%len(root)])
if __name__ == '__main__':
  main()