#include <cstdio>
#include <queue>
using namespace std;
struct node {
    long long q, w, x, id;
} nodes1[50010], nodes2[50010];
bool operator < (node a, node b) {
    return a.x > b.x;
}
bool vis[50010];
priority_queue<node> pq1, pq2;
priority_queue<int> nowq;
int n, k;
long long s, ans;
int main() {
    scanf("%d%d%lld", &n, &k, &s);
    for (int i = 1; i <= n; i++) {
        long long w, q;
        scanf("%lld%lld", &w, &q);
        nodes1[i].w = nodes2[i].w = nodes1[i].x = w;
        nodes1[i].q = nodes2[i].q = nodes2[i].x = q;
        nodes1[i].id = nodes2[i].id = i;
        pq1.push(nodes1[i]);
        pq2.push(nodes2[i]);
    }
    while (true) {
        while (vis[pq1.top().id]) pq1.pop();
        while (vis[pq2.top().id]) pq2.pop();
        long long sub1 = pq1.top().x;
        long long sub2 = pq2.top().x;
        if (nowq.size() == k) {
            if (nowq.empty()) {
                sub2 += 1e18;
            } else {
                sub2 += nowq.top();
            }
        }
        if (sub1 <= sub2) {
            if (sub1 > s) {
                break;
            }
            vis[pq1.top().id] = true;
            s -= sub1;
            ans++;
            pq1.pop();
        } else {
            if (sub2 > s) {
                break;
            }
            vis[pq2.top().id] = true;
            s -= sub2;
            ans++;
            if (nowq.size() == k) {
                nowq.pop();
                nowq.push(pq2.top().w - pq2.top().q);
            }
            pq2.pop();
        }
    }
    printf("%lld\n", ans);
    return 0;
}