// Guess Who's Back
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define endl '\n'
#define D(x) cerr << #x << " = " << (x) << '\n'
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
typedef long long ll;

const int N = 2e5 + 5;

int n;
int arr[N];
int par[N];

int fs(int x) {
  return x == par[x] ? x : par[x] = fs(par[x]);
}

int main()
{
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);

  for(int i = 0; i < N; i++) {
    par[i] = i;
  }

  cin >> n;
  for(int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  int ans = 0;
  for(int i = 0; i < n / 2; i++) {
    int j = n - 1 - i;
    int x = fs(arr[i]), y = fs(arr[j]);
    if(x != y) {
      ans++;
      par[x] = y;
    }
  }
  cout << ans << endl;
  return 0;
}

#include <bits/stdc++.h>
using namespace std;

// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;

// #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>

#define FS              ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll              long long int
#define ld              long double
#define pb              push_back
#define bp              __builtin_popcount
#define sz              size()
#define ff              first
#define ss              second
#define vll             vector<ll>
#define vbool           vector<bool>
#define vpll            vector<pair<ll,ll>>
#define pll             pair<ll,ll>
#define vllv            vector<vector<ll>>
#define setpri(x)       cout<<setprecision(x)<<fixed;
#define all(v)          v.begin(),v.end()
#define allr(v)         v.rbegin(),v.rend()
#define yesr {cout<<"YES"<<endl;return;}
#define nor {cout<<"NO"<<endl;return;}
// getline (std::cin,name);
ll MOD=1e9+7;
ll ceil1(ll n,ll x){return (n-1)/x+(n>0);}

ll gcd(ll a,ll b){return __gcd(a,b);}
ll lcm(ll a,ll b){return (max(a,b)/gcd(a,b))*min(a,b);}

ll pow1(ll n,ll m ,ll mod=MOD );
ll pow2(ll n,ll k);

ll modinv(ll n,ll mod=MOD){  return pow1(n,mod-2,mod);}

bool func(pair<ll,ll> &a,pair<ll,ll> &b ){
        if(a.ff != b.ff)return a.ff < b.ff;
        return a.ss > b.ss;
}

ll const N=(ll)3e5+11;
ll const LG=(ll)log2(N)+1;


void solve() {
		ll i,j,k,l,n,m,x,y,z,r;
		
		
		cin>>n;
		map<string,ll> mp;
		set<string> st;
		for(i=0;i<n;i++){
			string t;
			cin>>t;
			if(st.find(t)==st.end()){
				if(t[0]=='!'){
					mp[t.substr(1)]++;
				}
				
				else{
					mp[t]++;
				}
			}
			st.insert(t);
		}
		for(auto x:mp){
			if(x.ss>1){
				cout<<x.ff<<endl;
				return;
			}
		}
		cout<<"satisfiable\n";
		return;
		
		
		
		
}
int main(){
        FS;

        ll i,j,k,n,m,x,y,z,q;
        q=1;
        // cin>>q;
        for(ll tc=1;tc<=q;tc++){
                // cout<<"Case #"<<tc<<": ";
                solve();
        }
        return 0;
}


ll pow1(ll n,ll m,ll mod){
        if(m==0)return 1;

        if(m%2==0)return pow1((n*n)%mod,m/2,mod);

        return (pow1((n*n)%mod,m/2,mod)*n)%mod;
}

ll pow2(ll n,ll k){
        ll ans=1;
            while(k>0){
                if(k%2==1)ans=ans*n;
                n=n*n;
                k/=2;
            }
            return ans;
}