#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <vector>

#include <algorithm>

using namespace std;

struct node

{

    node *ch[];

    int sz;

    int v;

    int r;

    int sum;

    node(int v = ) : v(v)

    {

        r = rand();

        sz = ;

        ch[] = ch[] = NULL;

        sum = v;

    }

    int cmp(int k)

    {

        return k > v;

    }

    void maintain()

    {

        sz = ;

        sum = v;

        if(ch[] != NULL)

        {

            sz += ch[]->sz;

            sum += ch[]->sum;

        }

        if(ch[] != NULL)

        {

            sz += ch[]->sz;

            sum += ch[]->sum;

        }

    }

};

void rotate(node *&o, int d)

{

    node *k = o->ch[d^];

    o->ch[d^] = k->ch[d];

    k->ch[d] = o;

    o->maintain();

    k->maintain();

    o = k;

}

void insert(node *&o, int v)

{

    if(o == NULL) o = new node(v);

    else

    {

        int d = o->cmp(v);

        insert(o->ch[d], v);

        if(o->ch[d]->r > o->r) rotate(o, d^);

    }

    o->maintain();

}

void remove(node *&o, int v)

{

    if(v == o->v)

    {

        if(o->ch[] == NULL) o = o->ch[];

        else if(o->ch[] == NULL) o = o->ch[];

        else

        {

            int d = o->ch[]->r < o->ch[]->r ?  : ;

            rotate(o, d);

            remove(o->ch[d], v);

        }

    } else

    {

        int d = o->cmp(v);

        remove(o->ch[d], v);

    }

    if(o != NULL) o->maintain();

}

int query(node *o, int k)

{

    int s = o->ch[] == NULL ?  : o->ch[]->sz;

    int sum = o->ch[] == NULL ?  : o->ch[]->sum;

    if(s +  > k) return query(o->ch[], k);

    if(s +  == k) return sum + o->v;

    if(s +  < k) return sum + o->v + query(o->ch[], k - s - );

}

void del(node *o)

{

    if(o->ch[] != NULL) del(o->ch[]);

    if(o->ch[] != NULL) del(o->ch[]);

    delete o;

}

int main()

{

    int n, c, f;

    while(scanf("%d%d%d", &n, &c, &f) != EOF)

    {

        vector<pair<int, int> > a;

        for(int i = ; i < c; i++)

        {

            int x, y;

            scanf("%d%d", &x, &y);

            a.push_back(make_pair(x, y));

        }

        sort(a.begin(), a.end());

        node *r = NULL, *l = NULL;

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

            insert(r, a[c - i - ].second);

        for(int i = c - n /  - ; i >= ; i--)

            insert(l, a[i].second);

        int ans = -;

        for(int i = c - n /  - ; i >= n / ; i--)

        {

            remove(l, a[i].second);

            if(query(l, n / ) + query(r, n / ) + a[i].second <= f)

            {

                ans = a[i].first;

                break;

            }

            insert(r, a[i].second);

        }

        printf("%d\n", ans);

        del(l); del(r);

    }

    return ;

}