Help me in solving COSTPERM problem

help
,
1

My issue

how
for
1
1 2 3
answer will be 5

My code

#include <bits/stdc++.h>
using namespace std;
using ll=long long int;
int main() {
	// your code goes here
    ll t;
    cin>>t;
    while(t--)
    {
       ll n;
       cin>>n;
       ll arr[n];
       for(ll i=0;i<n;i++)
       {
           cin>>arr[i];
       }
       unordered_set<ll> st;
       ll be=arr[0];
       ll mov=be;
       st.insert(be);
       while(true)
       {
           if(be==arr[mov-1])
           {
               break;
           }
           else
           {
               mov=arr[mov-1];
               st.insert(mov);
           }
       }
       ll ans=0;
       for(ll i=1;i<=n;i++)
       {
           if(st.find(i)==st.end())
           {
               ans=ans+(i+1);
           }
       }
       cout<<ans<<endl;
    }
}

Problem Link: Costly Permutations Practice Coding Problem