#include<bits/stdc++.h>
using namespace std;
#define int long long
#define f first
#define s second
#define mp make_pair
#define eb emplace_back
#define pb push_back
typedef pair<int,int> pii;

const int mxn = 1e5+5;
int nex[mxn];

int32_t main() {
    ios_base::sync_with_stdio(false);cin.tie(0);
    int n;
    cin >> n;
    for(int i=1;i<=n;i++){
        int p;
        cin>>p;
        nex[i]=p;
    }
    int lc=0;
    for(int i=1;i<=n;i++){
        if(nex[i]==0)continue;
        int c=0;
        int u=i;
        while(true){
            int nn=nex[u];
            nex[u]=0;
            u=nn;
            c++;
            if(u==i)break;
        }
        lc = max(lc, c);
    }
    int ans=1;
    int cyc_len=0;
    for(int i=0;i<=n;i++){
        if(cyc_len>=lc-1)break;
        cyc_len+=(1ll<<i);
        ans++;
    }
    cout<<ans;
}