#include<algorithm>

#include<iostream>

#include<cstdio>

#include<queue>

#define int long long

using namespace std;

inline int rd(){

    int ret=,f=;char c;

    while(c=getchar(),!isdigit(c))f=c=='-'?-:;

    while(isdigit(c))ret=ret*+c-'',c=getchar();

    return ret*f;

}

priority_queue<int> Q;

inline void Push(int x){Q.push(-x);}

inline int Top(){return Q.empty()?<<:-Q.top();}

const int MAXN=;

int n,num,m;

int p[MAXN],q[MAXN];

int vis[MAXN];

int id[MAXN],iid[MAXN];

int ans=,cnt=;

bool cmp1(int x,int y){return q[x]<q[y];}

bool cmp2(int x,int y){return p[x]<p[y];}

signed main(){

    freopen("shopping.in","r",stdin);

    freopen("shopping.out","w",stdout);

    n=rd();num=rd();m=rd();

    for(int i=;i<=n;i++){

        p[i]=rd();q[i]=rd();

        id[i]=iid[i]=i;

    }

    sort(id+,id++n,cmp1);

    sort(iid+,iid++n,cmp2);

    for(int i=;i<=num;i++){

        if(ans+q[id[i]]>m) return cout<<cnt,;

        ans+=q[id[i]];cnt++;

    }

    for(int i=;i<=num;i++) Push(p[id[i]]-q[id[i]]),vis[id[i]]=;

    for(int i=;i<=n;i++){

        if(ans>m) return cout<<cnt-,;

        if(vis[iid[i]]) continue;

        if(q[iid[i]]+Top()>p[iid[i]]) {ans+=p[iid[i]],cnt++;continue;}

        ans+=q[iid[i]]+Top();cnt++;

        Q.pop();Push(p[iid[i]]-q[iid[i]]);

    }

    cout<<cnt-(ans>m);

    return ;

}