#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

void solve(){
    
}
using p = pair<int, int>;
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; cin >> n;
    vector<p> vp(n);
    rep(i, n){
        int m; cin >> m;
        if(i+1 <= m){
            vp[i] = {i+1, m};
        }else{
            vp[i] = {m, i+1};
        }
    }
    sort(all(vp));
    priority_queue<int, vector<int>, greater<int>> pq;
    ll ans = 0;
    rep(i, n){
        auto [j, m] = vp[i];
        while(!pq.empty() && pq.top() <= j)pq.pop();
        ans += pq.size();
        pq.push(m);
    }cout << ans << endl;
    

    return 0;
}