#include <bits/stdc++.h>
using namespace std;
using INT = long long;
int n;
int a[200010];
vector<int> B[200010];
void add(int u, int val) {
  for (; u <= n; u += u & -u) B[u].push_back(val);
}
int calc(int u, int val) {
  int ans = 0;
  for (; u; u -= u & -u) {
    int id = lower_bound(B[u].begin(), B[u].end(), val) - B[u].begin();
    ans += B[u].size() - id;
  }
  return ans;
}
int calc(int l, int r, int val) {
  if (l > r) return 0;
  return calc(r, val) - calc(l - 1, val);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  for (int i = 1; i <= n; i++) add(i, min(a[i], n));
  for (int i = 1; i <= n; i++) sort(B[i].begin(), B[i].end());
  INT ans = 0;
  for (int i = 1; i < n; i++) {
    ans += calc(i + 1, min(n, a[i]), i);
  }
  cout << ans << endl;
  return 0;
}
