#include <bits/stdc++.h>

using namespace std;

constexpr int N = 1e6 + 5;

int inv[N], a[N], s[N * 2];

signed main() {
    int n; scanf("%d%*d", &n);
    vector< pair<int, int> > p[2];
    for (int i = 1, x, y; i <= n; ++i) scanf("%d%d", &x, &y), p[0].push_back({x, i}), p[1].push_back({y, i});
    sort(p[0].begin(), p[0].end()), sort(p[1].begin(), p[1].end());
    for (int i = 1; i <= n; ++i) inv[p[0][i - 1].second] = i;
    for (int i = 1; i <= n; ++i) a[inv[p[1][i - 1].second]] = i;
    long long res = 1e18;
    for (int t = 1; t <= n; ++t) {
        rotate(a + 1, a + 2, a + n + 1);
        vector< pair<int, int> > seg;
        for (int i = 1; i <= n; ++i) {
            if (a[i] < i) seg.push_back({i, a[i] + n});
            else seg.push_back({i, a[i]}), seg.push_back({i + n, a[i] + n});
        }
        sort(seg.begin(), seg.end());
        long long sum = 0;
        for (int i = 1; i <= n * 2; ++i) s[i] = 0;
        for (auto x : seg | views::reverse | views::values) {
            for (int i = x; i; i -= i & -i) sum += s[i];
            for (int i = x; i <= n * 2; i += i & -i) ++s[i];
        }
        res = min(res, sum);
    }
    printf("%lld\n", res);
    return 0;
}