/** * @FileName a.cpp * @Author kanpurin * @Created 2020.06.11 01:58:36 **/ #include "bits/stdc++.h" using namespace std; typedef long long ll; template < typename T > struct BinaryIndexedTree { std::vector< T > data; BinaryIndexedTree(int sz) { data.assign(++sz, 0); } inline T sum(int k) { T ret = 0; for (++k; k > 0; k -= k & -k) ret += data[k]; return (ret); } inline T sum(int left, int right) { return sum(right) - sum(left - 1); } inline void add(int k, T x) { for (++k; k < data.size(); k += k & -k) data[k] += x; } int get(ll k) { ++k; int res = 0; int N = 1; while (N < (int)data.size()) N *= 2; for (int i = N / 2; i > 0; i /= 2) { if (res + i < (int)data.size() && data[res + i] < k) { k = k - data[res + i]; res = res + i; } } return res + 1; } void print() { std::cout << "[ "; for (int i = 0; i < data.size() - 1; i++) { std::cout << sum(i, i); if (i < data.size() - 2) cout << ", "; } std::cout << " ]" << endl; } }; int main() { int n, m; cin >> n >> m; BinaryIndexedTree< int > bit(m); ll ans = 0; vector< pair< int, int > > p(n); for (int i = 0; i < n; i++) { int a, b; cin >> a >> b; if (a > b) swap(a, b); p[i].first = a; p[i].second = b; } sort(p.begin(), p.end()); for (int i = 0; i < n; i++) { ans += bit.sum(p[i].first, p[i].second); bit.add(p[i].second, 1); } cout << ans << endl; return 0; }