N = int(input())
As = list(map(int, input().split()))
As = [a - 1 for a in As]
def solve(N, amida):
    cycles = [0] * N
    for idx in range(N):
        if cycles[idx]:
            continue
        find_cycle(N, amida, idx, cycles)
    uniq_cycles = set(cycles)
    for c in uniq_cycles:
        if c % 2 == 0:
            return False
    return True


def find_cycle(N, amida, idx, cycles):
    a = amida[idx]
    count = 1
    path = [idx]
    while a != idx:
        path.append(a)
        a = amida[a]
        count += 1
    for a in path:
        cycles[a] = count

if solve(N, As):
    print('Yes')
else:
    print('No')