A. Two Friends

Monocarp wants to throw a party. He has 𝑛 friends, and he wants to have at least 2 of them at his party.

The 𝑖-th friend's best friend is 𝑝𝑖. All 𝑝𝑖 are distinct, and for every 𝑖∈[1,𝑛], 𝑝𝑖≠𝑖.

Monocarp can send invitations to friends. The 𝑖-th friend comes to the party if both the 𝑖-th friend and the 𝑝𝑖-th friend receive an invitation (note that the 𝑝𝑖-th friend doesn't have to actually come to the party). Each invitation is sent to exactly one of the friends.

For example, if 𝑝=[3,1,2,5,4], and Monocarp sends invitations to the friends [1,2,4,5], then the friends [2,4,5] will come to the party. The friend 1 won't come since his best friend didn't receive an invitation; the friend 3 won't come since he didn't receive an invitation.

Calculate the minimum number of invitations Monocarp has to send so that at least 2 friends come to the party.