#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;
using P = pair<int, int>;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n; cin >> n;
    vector<int> p(n);
    for(int i = 0; i < n; i++) cin >> p[i];
    set<int> st;
    for(int i = 1; i <= n; i++) st.insert(i);
    vector<P> vp;
    for(int i = 0; i < n; i++){
        vp.push_back(P(2*i+2, i));
        vp.push_back(P(i+1, i));
    }
    sort(vp.begin(), vp.end(), greater<P>());
    ll ans = 0;
    vector<bool> ok(n);
    for(auto [score, i]: vp){
        if(ok[i]) continue;
        if((i+1)*2 == score){
            auto pt = st.upper_bound(p[i]);
            if(pt == st.end()){
                continue;
            }
            ans += i+1;
            st.erase(pt);
            ok[i] = true;
        }else{
            auto pt = st.lower_bound(p[i]);
            if(pt == st.end()){
                ans -= i+1;
                st.erase(st.begin());
            }else{
                st.erase(pt);
            }
        }
    }
    cout << ans << endl;
}