#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> ii;
#define fr first
#define sc second
#define mp make_pair

const int MAXN = 50010;
const ll inf = (1LL << 61);

int n, k;
ll budget;
ii ar[MAXN];

bool cmp(ii a, ii b)
{
    if (a.sc == b.sc)
        return a.fr > b.fr;
    return a.sc < b.sc;
}

bool delrem[MAXN], delcoup[MAXN], delswapp[MAXN];

int solve()
{
    ll cur = 0;
    int ans = 0;
    priority_queue<ii> coup;
    priority_queue<ii, vector<ii>, greater<ii> > rem, swapp;
    for (int i = 0; i < n; i++)
    {
        if (cur + ar[i].sc <= budget)
        {
            coup.push(mp(ar[i].sc, i));
            swapp.push(mp(ar[i].fr - ar[i].sc, i));
            cur += ar[i].sc;
            ans++;
        }
        else
        {
            rem.push(mp(ar[i].fr, i));
        }
    }
    int coupsize = coup.size();
    while (coupsize > k)
    {
        ll a;
        if (rem.empty() || coup.empty())
            a = inf;
        else a = rem.top().fr - coup.top().fr;
        ll b;
        if (swapp.empty())
            b = inf;
        else b = swapp.top().fr;
        if (min(a, b) + cur > budget)
        {
            cur -= coup.top().fr;
            rem.push(mp(ar[coup.top().sc].fr, coup.top().sc));
            delswapp[coup.top().sc] = true;
            ans--;
            coup.pop();
            coupsize--;
        }
        else if (b < a)
        {
            delcoup[swapp.top().sc] = true;
            delrem[swapp.top().sc] = true;
            cur += swapp.top().fr;
            swapp.pop();
            coupsize--;
        }
        else
        {
            delrem[rem.top().sc] = true;
            delswapp[coup.top().sc] = true;
            delswapp[rem.top().sc] = true;
            cur += b;
            rem.push(mp(ar[coup.top().sc].fr, coup.top().sc));
            coup.pop();
            rem.pop();
            coupsize--;
        }
        while (!rem.empty() && delrem[rem.top().sc])
            rem.pop();
        while (!coup.empty() && delcoup[coup.top().sc])
            coup.pop();
        while (!swapp.empty() && delswapp[swapp.top().sc])
            swapp.pop();
    }
    return ans;
}

int main()
{
    scanf("%d%d", &n, &k);
    scanf("%I64d", &budget);
    for (int i = 0; i < n; i++)
        scanf("%I64d%I64d", &ar[i].fr, &ar[i].sc);
    sort(ar, ar + n, cmp);
    printf("%d\n", solve());
}