#include <bits/stdc++.h>
using namespace std;
int a[200005];
long long b[200005];
struct persistent_seg_tree {
  struct data {
    int sum;
    data() : sum(0) {}
  };
  struct node {
    int l, r;
    data d;
    node() : l(0), r(0) {}
  };
  vector<node> nodes;
  vector<int> roots;
  int sz;
  void up(int id) {
    nodes[id].d.sum = nodes[nodes[id].l].d.sum + nodes[nodes[id].r].d.sum;
  }
  int newnode(int cpy) {
    int id = (int)nodes.size();
    node tmp = nodes[cpy];
    nodes.push_back(tmp);
    return id;
  }
  int add(int tp, int tl, int tr, int i, int v) {
    int id = newnode(tp);
    if (tl + 1 >= tr) {
      nodes[id].d.sum += v;
      return id;
    }
    int tmid = (tl + tr) / 2;
    if (i < tmid) {
      int nid = add(nodes[id].l, tl, tmid, i, v);
      nodes[id].l = nid;
    } else {
      int nid = add(nodes[id].r, tmid, tr, i, v);
      nodes[id].r = nid;
    }
    up(id);
    return id;
  }
  int getsum(int tp, int tl, int tr, int l, int r) {
    if (l <= tl && tr <= r) {
      return nodes[tp].d.sum;
    }
    int tmid = (tl + tr) / 2;
    int sum = 0;
    if (l < tmid) {
      sum += getsum(nodes[tp].l, tl, tmid, l, r);
    }
    if (r > tmid) {
      sum += getsum(nodes[tp].r, tmid, tr, l, r);
    }
    return sum;
  }
  void init(int range, int root_size) {
    sz = range;
    nodes.clear();
    roots.clear();
    nodes.reserve(root_size * (int)(log(sz * 2.0) / log(2.0) + 1.01));
    nodes.push_back(node());
    roots.reserve(root_size + 1);
    roots.push_back(0);
  }
  void add(int pos, int v) {
    int last = roots.back();
    roots.push_back(add(last, 0, sz, pos, v));
  }
  int getsum(int t, int l, int r) {
    if (t <= 0) return 0;
    if (r < l) return 0;
    if (t >= (int)roots.size()) t = (int)roots.size() - 1;
    return getsum(roots[t], 0, sz, l, r + 1);
  }
} tree;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  long long tmp = n;
  int ma = -1;
  for (int i = 1; i <= n; ++i) {
    cin >> b[i];
    a[i] = min(b[i], tmp);
    ma = max(ma, a[i]);
  }
  tree.init(ma + 1, 4 * n);
  for (int i = 1; i <= n; ++i) {
    tree.add(a[i], 1);
  }
  long long ans = 0;
  for (int i = 1; i <= n; ++i) {
    int r = min(n, a[i]);
    int l = i + 1;
    if (r >= l) ans += tree.getsum(r, i, n + 1) - tree.getsum(l - 1, i, n + 1);
  }
  cout << ans;
  return 0;
}
