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

const int N = 5e4 + 10;
struct node
{
	LL p, c;
} a[N];
bool cmp(node x, node y) { 
	return (x.c != y.c) ? x.c < y.c : x.p < y.p; 
}

priority_queue<LL> q;

int main()
{
	int n, k;
	LL m;
	scanf("%d%d%lld", &n, &k, &m);
	for (int i = 1; i <= n; i++)
		scanf("%lld%lld", &a[i].p, &a[i].c);
	sort(a + 1, a + 1 + n, cmp);
	LL sum = 0;
	for (int i = 1; i <= n; i++)
	{
		if (i <= k)
		{
			sum += a[i].c;
			q.push(a[i].p - a[i].c);
		}
		else
		{
			int x = q.top();
			if (x + a[i].c < a[i].p)
			{
				sum += x + a[i].c;
				q.pop();
				q.push(a[i].p - a[i].c);
			}
			else
				sum += a[i].p;
		}
		if (sum > m)
		{
			printf("%d\n", i - 1);
			return 0;
		}
	}
	printf("%d\n", n);
	return 0;
}