ACMNB.cpp

#include <bits/stdc++.h>
using namespace std;

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int n; cin >> n;
    n *= 2;
    vector<int> a(n);
    int sum = 0;
    for (auto &i : a) {
        int x, y;
        cin >> x >> y;
        sum += x;
        i = y - x;
    }
    sort(a.begin(), a.end());
    for (int i = 0; i < n / 2; i++) {
        sum += a[i];
    }
    cout << sum << '\n';
}