// >>> TEMPLATES #include using namespace std; using ll = long long; using ld = long double; #define int ll #define double ld #define rep(i,n) for (int i = 0; i < (int)(n); i++) #define rep1(i,n) for (int i = 1; i <= (int)(n); i++) #define repR(i,n) for (int i = (int)(n)-1; i >= 0; i--) #define rep1R(i,n) for (int i = (int)(n); i >= 1; i--) #define loop(i,a,B) for (int i = a; i B; i++) #define loopR(i,a,B) for (int i = a; i B; i--) #define all(x) (x).begin(), (x).end() #define allR(x) (x).rbegin(), (x).rend() #define pb push_back #define eb emplace_back #define mp make_pair #define fst first #define snd second #define INF (numeric_limits::max()/2-1) #ifdef LOCAL #include "debug.hpp" #define dump(...) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] ", dump_impl(#__VA_ARGS__, __VA_ARGS__) #define say(x) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] " << x << endl #define debug if (1) #else #define dump(...) (void)(0) #define say(x) (void)(0) #define debug if (0) #endif template using pque_max = priority_queue; template using pque_min = priority_queue, greater >; template ::value>::type> ostream& operator<<(ostream& os, T const& v) { bool f = true; for (auto const& x : v) os << (f ? "" : " ") << x, f = false; return os; } template ::value>::type> istream& operator>>(istream& is, T &v) { for (auto& x : v) is >> x; return is; } template istream& operator>>(istream& is, pair& p) { return is >> p.first >> p.second; } struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup; template struct FixPoint : private F { constexpr FixPoint(F&& f) : F(forward(f)) {} template constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward(x)...); } }; struct MakeFixPoint { template constexpr auto operator|(F&& f) const { return FixPoint(forward(f)); } }; #define MFP MakeFixPoint()| #define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__) template struct vec_impl { using type = vector::type>; template static type make_v(size_t n, U&&... x) { return type(n, vec_impl::make_v(forward(x)...)); } }; template struct vec_impl { using type = T; static type make_v(T const& x = {}) { return x; } }; template using vec = typename vec_impl::type; template auto make_v(Args&&... args) { return vec_impl::make_v(forward(args)...); } template void quit(T const& x) { cout << x << endl; exit(0); } template constexpr bool chmin(T& x, T const& y) { if (x > y) { x = y; return true; } return false; } template constexpr bool chmax(T& x, T const& y) { if (x < y) { x = y; return true; } return false; } template constexpr auto sumof(It b, It e) { return accumulate(b,e,typename iterator_traits::value_type{}); } template int sz(T const& x) { return x.size(); } template int lbd(C const& v, T const& x) { return lower_bound(v.begin(), v.end(), x)-v.begin(); } template int ubd(C const& v, T const& x) { return upper_bound(v.begin(), v.end(), x)-v.begin(); } // <<< // >>> BIT struct BIT { int n; vector v; // use v[1..n] BIT(int n) : n(n), v(n+1) {} int get(int i) const { return sum(i+1)-sum(i); } void set(int i, int x) { add(i,x-get(i)); } void add(int i, int x) { assert(0 <= i && i < n); for (i++; i <= n; i += i&(-i)) v[i] += x; } int sum(int r) const { // [0,r) assert(0 <= r && r <= n); int s = 0; for (int i = r; i > 0; i -= i&(-i)) s += v[i]; return s; } int sum(int l, int r) const { // [l,r) return sum(r)-sum(l); } }; // <<< // >>> reord void reord_impl(vector const&) { } template void reord_impl(vector const& idx, vector &v, Args&&... args) { vector t(v.size()); rep (i,v.size()) t[i] = v[idx[i]]; swap(v,t); reord_impl(idx, forward(args)...); } template ()(0,0))> void reord(Comp comp, vector &v, Args&&... args) { vector idx(v.size()); iota(idx.begin(), idx.end(), 0); sort(idx.begin(), idx.end(), comp); reord_impl(idx, v, args...); } template void reord(vector &v, Args&&... args) { vector idx(v.size()); iota(idx.begin(), idx.end(), 0); sort(idx.begin(), idx.end(), [&](int i, int j) { return v[i] < v[j]; }); reord_impl(idx, v, args...); } // <<< int32_t main() { int n,m; cin >> n >> m; vector a(n),b(n); rep (i,n) cin >> a[i] >> b[i]; rep (i,n) if (a[i] > b[i]) swap(a[i],b[i]); reord(a,b); int cnt = 0; BIT bit(m); rep (i,n) { cnt += bit.sum(a[i],b[i]+1); bit.add(b[i],1); } cout << cnt << endl; }