Buggy python submission (verdict: Runtime Error):
def main():
    N,K = map(int,input().split())
    As = list(map(int,input().split()))
    route = [0]
    pre = 0
    i = 0
    r_append = route.append
    for _ in range(N):
        i = As[i]-1
        if i in route:
            pre = route.index(i)
            route = route[pre:]
            break
        r_append(i)
        len_route += 1
    # print(route)
    mod = len(route)
    print(route[(K-pre)%mod]+1)

if __name__ == "__main__":
    main()

Fixed submission:
N,K = map(int,input().split())
As = list(map(int,input().split()))
towns = [0]*N
route = [0]
pre = 0
i = 0
towns[0] = 1
for _ in range(K):
    i = As[i]-1
    if towns[i]>0:
        pre = route.index(i)
        route = route[pre:]
        break
    route.append(i)
    towns[i] = 1
mod = len(route)
print(route[(K-pre)%mod]+1)

Buggy python submission (verdict: Runtime Error):
def main():
    N,K = map(int,input().split())
    As = list(map(int,input().split()))
    route = [0]
    pre = 0
    i = 0
    r_append = route.append
    for _ in range(N):
        i = As[i]-1
        if i in route:
            pre = route.index(i)
            route = route[pre:]
            break
        r_append(i)
        len_route += 1
    # print(route)
    mod = len(route)
    print(route[(K-pre)%mod]+1)

if __name__ == "__main__":
    main()

Fixed submission:
N,K = map(int,input().split())
As = list(map(int,input().split()))
towns = [0]*N
route = [0]
pre = 0
i = 0
towns[0] = 1
for _ in range(K):
    i = As[i]-1
    if towns[i]>0:
        pre = route.index(i)
        route = route[pre:]
        break
    route.append(i)
    towns[i] = 1
mod = len(route)
print(route[(K-pre)%mod]+1)

Buggy python submission (verdict: Time Limit Exceeded):
N,K = map(int,input().split())
As = list(map(int,input().split()))
route = [0]
pre = 0
i = 0
len_route = 1
for k in range(K):
    i = As[i]-1
    if i in route:
        pre = route.index(i)
        route = route[pre:]
        len_route -= pre
        break
    route.append(i)
    len_route += 1
# print(route)
mod = len_route
print(route[(K-pre)%mod]+1)

Fixed submission:
N,K = map(int,input().split())
As = list(map(int,input().split()))
towns = [0]*N
route = [0]
pre = 0
i = 0
towns[0] = 1
for _ in range(K):
    i = As[i]-1
    if towns[i]>0:
        pre = route.index(i)
        route = route[pre:]
        break
    route.append(i)
    towns[i] = 1
mod = len(route)
print(route[(K-pre)%mod]+1)

Buggy python submission (verdict: Time Limit Exceeded):
N,K = map(int,input().split())
As = list(map(int,input().split()))
route = [0]
pre = 0
i = 0
for k in range(K):
    i = As[i]-1
    if i in route:
        pre = route.index(i)
        route = route[pre:]
        break
    route.append(i)
#print(route)
mod = len(route)
print(route[(K-pre)%mod]+1)

Fixed submission:
N,K = map(int,input().split())
As = list(map(int,input().split()))
towns = [0]*N
route = [0]
pre = 0
i = 0
towns[0] = 1
for _ in range(K):
    i = As[i]-1
    if towns[i]>0:
        pre = route.index(i)
        route = route[pre:]
        break
    route.append(i)
    towns[i] = 1
mod = len(route)
print(route[(K-pre)%mod]+1)

Buggy python submission (verdict: Time Limit Exceeded):
N,K = map(int,input().split())
As = list(map(int,input().split()))
mod = 0
route = [0]
pre = 0
i = 0
for k in range(K):
    i = As[i]-1
    if i in route:
        pre = route.index(i)
        route = route[pre:]
        break
    route.append(i)
# print(route)
mod = len(route)
print(route[(K-pre)%mod]+1)

Fixed submission:
N,K = map(int,input().split())
As = list(map(int,input().split()))
towns = [0]*N
route = [0]
pre = 0
i = 0
towns[0] = 1
for _ in range(K):
    i = As[i]-1
    if towns[i]>0:
        pre = route.index(i)
        route = route[pre:]
        break
    route.append(i)
    towns[i] = 1
mod = len(route)
print(route[(K-pre)%mod]+1)