Freshman's Database

import sys

if __name__ == '__main__':
    n = int(sys.stdin.readline())

    values = sys.stdin.readline().split()
    visited = [0]*n

    count = 0
    for i in range(n):
        if not visited[i]:
            j = i
            cycle_visited = [0]*n

            while True:
                if not cycle_visited[j]:
                    cycle_visited[j] = 1
                    j = int(values[j]) - 1
                else:
                    if not visited[j]:
                        count += 1
                    break
            visited = [sum(x) for x in zip(visited, cycle_visited)]
    print(count)

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: RUNTIME ERROR

Test 4

Verdict: RUNTIME ERROR

Test 5

Verdict: RUNTIME ERROR

Test 6

Verdict: RUNTIME ERROR

Test 7

Verdict: RUNTIME ERROR

Test 8

Verdict: RUNTIME ERROR

Test 9

Verdict: RUNTIME ERROR

Test 10

Verdict: RUNTIME ERROR