// Problem: B. 省钱
// Contest: undefined - NOIP2024训练赛 15
// URL: http://noi.ac/contest/1167/problem/2639
// Memory Limit: 1024 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
#define int long long
#define x first
#define y second

using namespace std;

const int N = 5e4 + 10;

int n, k, m, ans;
int c[N], p[N];
bool vis[N];

priority_queue<pair<int, int>, vector<pair<int, int> >, greater<pair<int, int> > > price, afteruse;
priority_queue<int, vector<int>, greater<int> > change;

signed main()
{
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n >> k >> m;
	for(int i = 1; i <= n; i ++)
	{
		cin >> p[i] >> c[i];
		price.push({p[i], i});
		afteruse.push({c[i], i});
	}
	for(int i = 1; i <= k; i ++) change.push(0);
	while(!price.empty())
	{
		auto cowa = price.top();
		auto cowb = afteruse.top();
		if(vis[cowa.y]) {price.pop(); continue;}
		if(vis[cowb.y]) {afteruse.pop(); continue;}
		if(!change.empty() && change.top() > cowa.x - cowb.x)
		{
			m -= cowa.x; price.pop();
			vis[cowa.y] = true;
		}
		else
		{
			m -= cowb.x + change.top();
			if(!change.empty()) change.pop();
			afteruse.pop();
			vis[cowb.y] = true;
			change.push(p[cowb.y] - c[cowb.y]);
		}
		if(m >= 0) ans ++;
		else break;
	}
	cout << ans << '\n';
	return 0;
}