Audit Sale

#include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 5;

struct Element {
    int price;
    int prob;

    bool operator < (const Element &o) const {
        return price * 100 + o.price * o.prob > o.price * 100 + price * prob;
    }
} a[N];

long long prefix[N];
long long suffix[N];

int n, m, k;

long long solve() {
    sort(a + 1, a + 1 + n);

    multiset<int> S;
    long long sum = 0;
    for (int i = 1; i <= n; ++i) {
        S.insert(a[i].price);
        sum += a[i].price;
        if (S.size() > k) {
            sum -= *S.begin();
            S.erase(S.begin());
        }
        prefix[i] = sum * 100;
    }

    S.clear(); sum = 0;
    for (int i = n; i >= 1; --i) {
        S.insert(a[i].price * a[i].prob);
        sum += a[i].price * a[i].prob;
        if (S.size() > (m - k)) {
            sum -= *S.begin();
            S.erase(S.begin());
        }
        suffix[i] = sum;
    }

    long long ans = 0;
    for (int i = k; i + (m - k) <= n; ++i) {
        ans = max(ans, prefix[i] + suffix[i + 1]);
    }

    return ans;
}

int main() {
    cin >> n >> m >> k;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i].price;
        cin >> a[i].prob;
    }

    cout << solve() << endl;
    return 0;
}