/*

* Created:     2016年03月27日 14时41分47秒 星期日

* Author:      Akrusher

*

*/

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <cmath>

#include <ctime>

#include <iostream>

#include <algorithm>

#include <string>

#include <vector>

#include <deque>

#include <list>

#include <set>

#include <map>

#include <stack>

#include <queue>

#include <numeric>

#include <iomanip>

#include <bitset>

#include <sstream>

#include <fstream>

using namespace std;

#define rep(i,a,n) for (int i=a;i<n;i++)

#define per(i,a,n) for (int i=n-1;i>=a;i--)

#define inll(n) scanf("%I64d",&(n))

#define inll2(x1,x2) scanf("%I64d%I64d",&(x1),&(x2))

#define inlld(n) scanf("%lld",&(n))

#define inlld2(x1,x2) scanf("%lld%lld",&(x1),&(x2))

#define inf(n) scanf("%f",&(n))

#define inf2(x1,x2) scanf("%f%f",&(x1),&(x2))

#define inlf(n) scanf("%lf",&(n))

#define inlf2(x1,x2) scanf("%lf%lf",&(x1),&(x2))

#define inc(str) scanf("%c",&(str))

#define ins(str) scanf("%s",(str))

#define out(x) printf("%d\n",(x))

#define out2(x1,x2) printf("%d %d\n",(x1),(x2))

#define outf(x) printf("%f\n",(x))

#define outlf(x) printf("%lf\n",(x))

#define outlf2(x1,x2) printf("%lf %lf\n",(x1),(x2));

#define outlld(x) printf("%lld\n",(x))

#define outc(str) printf("%c\n",(str))

#define pb push_back

#define mp make_pair

#define fi first

#define se second

#define SZ(x) ((int)(x).size())

#define mem(X,Y) memset(X,Y,sizeof(X));

typedef vector<int> vec;

typedef long long ll;

typedef pair<int,int> P;

const int dx[]={,,-,},dy[]={,,,-};

const int INF=0x3f3f3f3f;

const ll mod=1e9+;

ll powmod(ll a,ll b) {ll res=;a%=mod;for(;b;b>>=){if(b&)res=res*a%mod;a=a*a%mod;}return res;}

const bool AC=true;

struct point{

ll a;

ll b;

};

point p[];

ll l[];

ll r[];

bool cmp(point x,point y){

 return x.a>y.a;

}

int main()

{

    ll c,n,ans,sum,sum1,sum2,f;

    while(scanf("%lld %lld %lld",&c,&n,&f)==){

    rep(i,,n)

    inlld2(p[i].a,p[i].b);

    sort(p,p+n,cmp);

    sum1=sum2=;sum=;

    priority_queue <int> que1;

    priority_queue <int> que2;

    mem(l,);

    mem(r,);

    rep(i,,n){ //遍历数组,找出left[i],right[i];

    if(i<c/){  //i左边的数少于c/2时,全部加入队列

    sum1+=p[i].b;

    que1.push(p[i].b);

    }

    else{

    l[i]=sum1;

    if(p[i].b<que1.top()){

    sum1-=que1.top(); //更新最小值

    sum1+=p[i].b;

    que1.pop();

    que1.push(p[i].b);

    }

    }

    }

    per(i,,n){

    if(i>=n-c/){

    sum2+=p[i].b;

    que2.push(p[i].b);

    }

    else{

    r[i]=sum2;

    if(p[i].b<que2.top()){

    sum2-=que2.top();

    sum2+=p[i].b;

    que2.pop();

    que2.push(p[i].b);

    }

    }

    }

    ans=-;

    rep(i,c/,n-c/){

    sum=p[i].b+l[i]+r[i];

    if(sum<=f){

    ans=p[i].a;

    break;

    }

    }

    outlld(ans);

    }

    return ;

}