#pragma GCC optimize("O3")

#include "bits/stdc++.h"
#include <stdio.h>
#include "atcoder/all"
#include <boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;

using namespace std;
using namespace atcoder;

using ll = long long;
using ull = unsigned long long;
using mint = modint998244353;
using mint2 = modint1000000007;
const double eps = 1e-9;

#define OVERLOAD3(_1, _2, _3, call,...) call
#define REP0(n) for (ll i = 0; i < ll(n); ++i)
#define REP1(i, n) for (ll i = 0; i < ll(n); ++i)
#define REP2(i, a, b) for (ll i = ll(a); i < ll(b); ++i)
#define REP(...) OVERLOAD3(__VA_ARGS__, REP2, REP1, REP0)(__VA_ARGS__)
#define RREP0(n) for (ll i = ll(n) - 1; i >= 0; --i)
#define RREP1(i, n) for (ll i = ll(n) - 1; i >= 0; --i)
#define RREP2(i, a, b) for (ll i = ll(a) - 1; i >= b; --i)
#define RREP(...) OVERLOAD3(__VA_ARGS__, RREP2, RREP1, RREP0)(__VA_ARGS__)
#define REPE(i, c) for (auto&& i : c)
#define TCASE() ll _ttt; cin >> _ttt; while(_ttt--)

template<class... T> void COMMON_IN(T&... a) { (cin >> ... >> a); }
#define LI(...) ll __VA_ARGS__; COMMON_IN(__VA_ARGS__);
#define SI(...) string __VA_ARGS__; COMMON_IN(__VA_ARGS__);

using vl = vector<ll>; using vvl = vector<vl>; using vvvl = vector<vvl>;
#define VLI(a, n) vector<ll> a; a.assign(n, 0); for(auto& x : a) cin >> x;
#define DLI(a, n) deque<ll> a; a.assign(n, 0); for(auto& x : a) cin >> x;
#define VSI(a, n) vector<string> a; a.assign(n, ""); for(auto& x : a) cin >> x;
#define VVLI(a, n, m) vector<vector<ll>> a(n, vector<ll>(m)); for(auto& x : a) for(auto& y : x) cin >> y;
using vd = vector<double>; using pl = pair<ll, ll>; using vpl = vector<pl>; using vvpl = vector<vpl>;

struct uv { ll u; ll v; };
struct uvc { ll u; ll v; ll c = 1; };
#define VUVI(a, n) vector<uv> a; a.assign(n, {0, 0}); for(auto& x : a) {cin >> x.u >> x.v; x.u--; x.v--;}
#define VUVCI(a, n) vector<uvc> a; a.assign(n, {0, 0, 0}); for(auto& x : a) {cin >> x.u >> x.v >> x.c; x.u--; x.v--;}
vvl to_edge(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) ret[x.u].emplace_back(x.v); return ret; }
vvl to_edge_d(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) { ret[x.u].emplace_back(x.v); ret[x.v].emplace_back(x.u); } return ret; }
vvpl to_edge_d(const ll n, const vector<uvc>& v) { vvpl ret(n); for (auto& x : v) { ret[x.u].emplace_back(x.v, x.c); ret[x.v].emplace_back(x.u, x.c); } return ret; }

template <class T = long long> using pql = priority_queue<T>;
template <class T = long long> using pqg = priority_queue<T, vector<T>, greater<T>>;
using vm = vector<mint>; using vvm = vector<vm>;

template <class T> requires std::is_base_of_v<atcoder::internal::modint_base, T> ostream& operator<<(ostream& os, const T& v) { os << v.val(); return os; }
void yn(bool f) { std::cout << (f ? "Yes" : "No") << "\n"; };
template<class T> void ov(const T& v) { for (auto it = v.begin(); it != v.end(); it++) { if (it != v.begin()) cout << " "; cout << *it; } };
template<class T> void ovn(const T& v) { ov(v); cout << "\n"; };

const ll llhuge = 1LL << 61; //十分でかいが多少足しても溢れない数値
auto gmax(const auto& a, const auto& b) { return a > b ? a : b; };
auto gmin(const auto& a, const auto& b) { return a < b ? a : b; };
bool chmin(auto& a, const auto& b) { const auto olda = a; a = gmin(a, b); return olda != a; }
bool chmax(auto& a, const auto& b) { const auto olda = a; a = gmax(a, b); return olda != a; }
void sort(auto& v) { std::ranges::sort(v); };
void rev(auto& v) { std::ranges::reverse(v); };
template<class T> auto p_sum(const T& v) { T ret(v.size()); std::partial_sum(begin(v), end(v), ret.begin()); return ret; };
template<class T, class K = T::key_type, class V = T::mapped_type> [[nodiscard]] V myat(const T& mp, const K& key) { return mp.find(key) == mp.end() ? V() : mp.at(key); }
long long ceil(const long long a, const long long b) { return (a + b - 1) / b; }
//セグ木(sum)
ll op(ll a, ll b) { return a + b; }
ll e() { return 0; }
using st = segtree<ll, op, e>;

struct lr {
    ll l;
    ll r;
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    LI(n);

    vector<st> segs;
	segs.reserve(1000);
    REP(i, 1000) segs.emplace_back(st(1000));
	vector<map<ll, ll>> mp(1000);
    vvl use(1000);
	REP(i, 1000) use[i].assign(1000, 0);

    vector<lr> a(n);
    REP(i, n) {
        LI(l, r);
		l--; r--;
		a[i] = { l, r };
		mp[l / 1000][r] = 1;
    }

    REP(i, 1000) {
        ll cnt = 0;
		for (auto& [k, v] : mp[i]) mp[i][k] = cnt++;
    }

    ll ans = 0;
    REP(i, n) {
        ll l = a[i].l;
        ll r = a[i].r;

        REP(bi, l / 1000) {
            ll v = 1000;
            auto it = mp[bi].lower_bound(r);
            if (it != mp[bi].end()) v = it->second;
			ans += segs[bi].prod(v, 1000);
        }
        REP(j, l % 1000) {
            if (r < use[l/1000][j]) ans++;
		}

		segs[l / 1000].set(mp[l / 1000][r], 1);
		use[l / 1000][l % 1000] = r;
    }
	cout << ans << "\n";

}