Problem:
Score : 300 points

Problem Statement

There is an empty array.
The following N operations will be performed to insert integers into the array.
In the i-th operation (1≤i≤N), b_i copies of an integer a_i are inserted into the array.
Find the K-th smallest integer in the array after the N operations.
For example, the 4-th smallest integer in the array \{1,2,2,3,3,3\} is 3.

Constraints

1≤N≤10^5

1≤a_i,b_i≤10^5

1≤K≤b_1…+…b_n

All input values are integers.

Input

Input is given from Standard Input in the following format:

N K
a_1 b_1
:
a_N b_N

Output

Print the K-th smallest integer in the array after the N operations.

Sample Input 1

3 4
1 1
2 2
3 3

Sample Output 1

3

The resulting array is the same as the one in the problem statement.

Sample Input 2

10 500000
1 100000
1 100000
1 100000
1 100000
1 100000
100000 100000
100000 100000
100000 100000
100000 100000
100000 100000

Sample Output 2

1

Solution in C++ (GCC 9.2.1) (judge verdict: Accepted)

#include<bits/stdc++.h>
using namespace std;


void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i : x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}

#define fo(i, n) for(int i=0; i<n; i++)
#define Fo(i, k, n) for(int i=k; i<n; i++)
#define w(x)  int x; cin>>x; while(x--)
#define watch(x) cout << (#x) << " is " << (x) << "\n"
#define watch2(x,y) cout <<(#x)<<" is "<<(x)<<" and "<<(#y)<<" is "<<(y)<<"\n"
#define watch3(x,y,z) cout <<(#x)<<" is "<<(x)<<" and "<<(#y)<<" is "<<(y)<<" and "<<(#z)<<" is "<<(z)<<"\n"
#define watch4(x,y,z,q) cout <<(#x)<<" is "<<(x)<<" and "<<(#y)<<" is "<<(y)<<" and "<<(#z)<<" is "<<(z)<<" and "<<(#q)<<" is "<<(q)<<"\n"
#define MOD 1000000007
#define INF 1000000007;
#define F first
#define S second
#define pb(x) push_back(x);


#define ll  long long
#define all(c) (c).begin(),(c).end()
#define endl "\n"

typedef vector<int> vl;
typedef vector< vl > vvl;
typedef pair< int, int> pll;
typedef map< int, int> mll;


#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif





void c_p_c()
{
#ifndef ONLINE_JUDGE
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}
void parray(int a[], int n) {
	for (int i = 0; i < n; i++) {
		cout << a[i] << " ";
	}
	cout << endl;
}

int main() {
	ll i, n, m, k, c = 0, sum = 0;
	c_p_c();
	ll no;

	cin >> n >> m;
	vector<pair<ll,ll>> v;
	for (int i = 0; i < n; ++i)
	{
		/* code */
		ll a,b;
		cin>>a>>b;
		v.pb(make_pair(a,b));
	}
	sort(all(v));
	for (int i = 1; i < n; ++i)
	{
		/* code */
		v[i].S+=v[i-1].S;
	}


	// for(auto it : v)
	// 	cout<<it.F<<" "<<it.S<<endl;


	for (int i = 0; i < n; ++i)
	{
		if(v[i].S>=m)
		{
			cout<<v[i].F<<endl;
			return 0;
		}
	}


	return 0;
}