#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize(2)
//#pragma GCC optimize(3, "Ofast", "inline")
#define hh putchar('\n')
#define kg putchar(' ')
#define debug puts("debug")
#define int long long
//#define int __int128
namespace quickread{
	template<typename T> void read(T &x){
		x=0;char c=getchar();T neg=0;
		while(!isdigit(c)) neg|=!(c^'-'),c=getchar();
		while(isdigit(c)) x=(x<<3)+(x<<1)+(c^48),c=getchar();
		if(neg) x=(~x)+1;
	}
	template<typename T> void write(T x){
		if(x<0) putchar('-'),x=~x+1;
		if(x>9) write(x/10);
		putchar(x%10^48);
	}
	inline string readstr(){
    	char ch=getchar();string str="";
		while(!isalnum(ch)) ch=getchar();
		while(isalnum(ch)){str+=ch;ch=getchar();}
		return str;
	}
	inline char readchar(){
		char ch=getchar();
		while(!isalnum(ch)) ch=getchar();
		return ch;
	}
	inline void putstr(string s){
		int len=s.length();
		for(int i=0;i<len;++i) putchar(s[i]);
	}
}
using namespace quickread;
const int N=2e5+10,inf=2147483647;
	#define mid (l+r>>1)
	int cnt=0,a[N];
	struct node{int value,siz,ls,rs;};
	node segment_tree[N<<5];
	int build(int l,int r){
		int p=++cnt;
		if(l^r) segment_tree[p].ls=build(l,mid),segment_tree[p].rs=build(mid+1,r);
		return p;
	}
	int update(int k,int l,int r,int p){
		int x=++cnt;
		segment_tree[x]=segment_tree[p],++segment_tree[x].siz,segment_tree[x].value+=a[k];
		if(l^r){
			if(k<=mid) segment_tree[x].ls=update(k,l,mid,segment_tree[x].ls);
			else segment_tree[x].rs=update(k,mid+1,r,segment_tree[x].rs);
		}
		return x;
	}
	int query(int lp,int rp,int l,int r,int k){
		int siz=segment_tree[segment_tree[rp].ls].siz-segment_tree[segment_tree[lp].ls].siz;
		int value=segment_tree[segment_tree[rp].ls].value-segment_tree[segment_tree[lp].ls].value;
		if(l^r){
			if(k<=siz) return query(segment_tree[lp].ls,segment_tree[rp].ls,l,mid,k);
			else return query(segment_tree[lp].rs,segment_tree[rp].rs,mid+1,r,k-siz)+value;
		}
		return a[l]*k;
	}
int n,m,k,maxf,midd,root[N],ans=-1;
struct csp{int val1,val2;};
bool operator <(const csp& A,const csp& B){return A.val1<B.val1;}
csp b[N];
signed main(){
//	ios::sync_with_stdio(0);
//	cin.tie(0);cout.tie(0);
	read(n),read(m),read(maxf),midd=n/2;
	for(int i=1;i<=m;++i) read(b[i].val1),read(b[i].val2),a[i]=b[i].val2;
	sort(a+1,a+m+1),sort(b+1,b+m+1);
	k=unique(a+1,a+m+1)-a-1;
	root[0]=build(1,k);
	for(int i=1;i<=m;++i){
		int x=lower_bound(a+1,a+k+1,b[i].val2)-a;
		root[i]=update(x,1,k,root[i-1]);
	}
	for(int i=1+(m-1)/2,val1,val2;i<=m-m/2;++i){
		val1=query(root[0],root[i-1],1,k,midd);
		val2=query(root[i],root[m],1,k,midd);
		if(val1+val2+b[i].val2<=maxf) ans=max(ans,b[i].val1);
	}
	write(ans);
	return 0;
}

$record$