#include "bits/stdc++.h"

using ll = long long;
using namespace std;

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    vector<pair<int, int>> a(n);

    for (auto &[x, y] : a) {
        cin >> x >> y;
    }

    ranges::sort(a);

    int l = 0;
    int r = n;

    while (r - l > 1) {
        int m = (l + r) / 2;

        auto check = [&]() {
            int cnt = m;
            for (int i = 0; i < n - m; i++) {
                if (a[i].first <= cnt) {
                    cnt += 1;
                } else {
                    return false;
                }
            }

            return true;
        };

        if (check()) {
            r = m;
        } else {
            l = m;
        }
    }

    cout << l << '\n';
    return 0;
}