#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n,k,s;
pair<ll,ll>p[50005];
priority_queue<ll,vector<ll>,greater<ll> >pq;
int rt=0,tot=0;
int tr[50005][2],sz[50005],dat[50005];
ll val[50005],su[50005];
int newnode(int x){
	tot++;
	tr[tot][0]=tr[tot][1]=0;
	val[tot]=su[tot]=x;
	sz[tot]=1;
	dat[tot]=rand();
	return tot;
}
void pushup(int x){
	sz[x]=sz[tr[x][0]]+sz[tr[x][1]]+1;
	su[x]=su[tr[x][0]]+su[tr[x][1]]+val[x];
}
void split(int x,ll v,int &tx,int &ty){
	if(x==0){
		tx=ty=0;
		return;
	}
	if(v>=val[x]){
		tx=x;
		split(tr[x][1],v,tr[tx][1],ty);
	}
	else{
		ty=x;
		split(tr[x][0],v,tx,tr[ty][0]);
	}
	pushup(x);
}
int merge(int x,int y){
	if(x==0 || y==0)return x+y;
	if(dat[x]<dat[y]){
		tr[x][1]=merge(tr[x][1],y);
		pushup(x);
		return x;
	} 
	else{
		tr[y][0]=merge(x,tr[y][0]);
		pushup(y);
		return y;
	}
}
int query(int x,ll v){
	if(!x)return 0;
	if(v<su[tr[x][0]])return query(tr[x][0],v);
	if(v<su[tr[x][0]]+val[x])return sz[tr[x][0]];
	return query(tr[x][1],v-su[tr[x][0]]-val[x])+sz[tr[x][0]]+1;
}
int main(){
//	freopen("N2639.in","r",stdin);
//	freopen("N2639.out","w",stdout);
	scanf("%lld%lld%lld",&n,&k,&s);
	for(int i=1;i<=n;i++)scanf("%lld%lld",&p[i].second,&p[i].first);
	ll delta=0,sum=0;
	sort(p+1,p+n+1);
	int ans=0;
	for(int i=1;i<k;i++)pq.push(p[i].second-p[i].first);
	for(int i=1;i<k;i++){
		sum+=p[i].second,delta+=p[i].second-p[i].first;
		if(sum-delta>s){
			printf("%d",i-1);
			return 0;
		}
		ans=i;
	}
	for(int i=k;i<=n;i++){
		int tx,ty;
		split(rt,p[i].second,tx,ty);
		rt=merge(merge(tx,newnode(p[i].second)),ty);
	}
	for(int i=k;i<=n;i++){
		pq.push(p[i].second-p[i].first);
		sum+=p[i].second;
		delta+=p[i].second-p[i].first;
		while(pq.size()>k){
			delta-=pq.top();
			pq.pop();
		}
//		printf("%d %lld %lld\n",i,sum,delta);
		if(sum-delta>s)break;
		int tx,ty,tz;
		split(rt,p[i].second,tx,tz);
		split(tx,p[i].second-1,tx,ty);
		ty=merge(tr[ty][0],tr[ty][1]);
		rt=merge(merge(tx,ty),tz);
		ans=max(ans,i+query(rt,s-(sum-delta)));
	}
	printf("%d",ans);
	return 0;
	//quod erat demonstrandum
}