#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
struct Node {
    int height;
    int weight;
} a[N];
int res;
bool cmp(Node a, Node b) {
    if (a.height != b.height)
        return a.height < b.height;
    return a.weight < b.weight;
}

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++)
        cin >> a[i].height >> a[i].weight;

    // 冒泡排序
    for (int i = 0; i < n; i++)
        for (int j = i + 1; j < n; j++)
            if (cmp(a[i], a[j])) {
                swap(a[i], a[j]);
                res++;
            }
    cout << res << endl;
    return 0;
}