#include using namespace std; using i64 = int64_t; using vi = vector; using vvi = vector; class RangeCount { const int ST_SIZE = (1 << 20) - 1; int n; vi data; vvi segtree; void init(int k, int l, int r) { if (r - l == 1) { segtree[k].push_back(data[l]); } else { int lch = k * 2 + 1; int rch = k * 2 + 2; init(lch, l, (l + r) / 2); init(rch, (l + r) / 2, r); segtree[k].resize(r - l); merge(segtree[lch].begin(), segtree[lch].end(), segtree[rch].begin(), segtree[rch].end(), segtree[k].begin()); } } // number of x in [i, j) int query(int i, int j, i64 x, int k, int l, int r) { if (j <= l || r <= i) { return 0; } if (i <= l && r <= j) { return upper_bound(segtree[k].begin(), segtree[k].end(), x) - segtree[k].begin(); } int lc = query(i, j, x, k * 2 + 1, l, (l + r) / 2); int rc = query(i, j, x, k * 2 + 2, (l + r) / 2, r); return lc + rc; } public: RangeCount(vi v) { n = v.size(); data = vi(v); segtree = vvi(ST_SIZE); init(0, 0, n); } int exact(int i, int j, i64 x) { return query(i, j, x, 0, 0, n) - query(i, j, x - 1, 0, 0, n); } int le(int i, int j, i64 x) { return query(i, j, x, 0, 0, n); } int lt(int i, int j, i64 x) { return query(i, j, x - 1, 0, 0, n); } int ge(int i, int j, i64 x) { return query(i, j, 1e18, 0, 0, n) - query(i, j, x - 1, 0, 0, n); } int gt(int i, int j, i64 x) { return query(i, j, 1e18, 0, 0, n) - query(i, j, x, 0, 0, n); } }; int main() { int n; cin >> n; vi vs(n); i64 ans = 0; for (int i = 0; i < n; i++) { cin >> vs[i]; vs[i]--; } RangeCount cnt(vs); for (int i = 0; i < n; i++) { if (vs[i] >= i) { ans += cnt.ge(0, i, vs[i]); ans += cnt.le(i, vs[i] + 1, vs[i]) - 1; ans += cnt.le(vs[i] + 1, n + 1, vs[i]); } else { ans += cnt.ge(0, vs[i], vs[i]); ans += cnt.ge(vs[i], i + 1, vs[i]) - 1; ans += cnt.le(i + 1, n + 1, i); } } cout << ans / 2 << endl; }