using System; using static System.Console; using System.Linq; using System.Collections.Generic; using System.Globalization; class Program { static int NN => int.Parse(ReadLine()); static int[] NList => ReadLine().Split().Select(int.Parse).ToArray(); static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray(); static int[] NMi => ReadLine().Split().Select(c => int.Parse(c) - 1).ToArray(); static int[][] NMap(int n) => Enumerable.Repeat(0, n).Select(_ => NMi).ToArray(); static string[] SList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => ReadLine()).ToArray(); static long[] LList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => long.Parse(ReadLine())).ToArray(); public static void Main() { Solve(); } static void Solve() { var n = NN; var map = NArr(n); var ans = 0L; Array.Sort(map, (l, r) => l[0].CompareTo(r[0])); var ft = new FenwickTree(1_000_001); for (var i = 0; i < n; ++i) ft.Add(map[i][1], 1); for (var i = 0; i < n; ++i) { ans += ft.Sum(map[i][1] - 1) - ft.Sum(map[i][0]); ft.Add(map[i][1], -1); } WriteLine(ans); } class FenwickTree { int size; long[] tree; public FenwickTree(int size) { this.size = size; tree = new long[size + 2]; } public void Add(int index, int value) { ++index; for (var x = index; x <= size; x += (x & -x)) tree[x] += value; } /// 先頭からindexまでの和(include index) public long Sum(int index) { if (index < 0) return 0; ++index; var sum = 0L; for (var x = index; x > 0; x -= (x & -x)) sum += tree[x]; return sum; } public long Get(int index) { if (index == 0) return Sum(0); return Sum(index) - Sum(index - 1); } /// Sum(x) >= value となる最小のxを求める // 各要素は非負であること public int LowerBound(long value) { if (value < 0) return -1; var x = 0; var b = 1; while (b * 2 <= size) b <<= 1; for (var k = b; k > 0; k >>= 1) { if (x + k <= size && tree[x + k] < value) { value -= tree[x + k]; x += k; } } return x; } } }