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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

    #include <iostream>
    #include <vector>
     
    int main(){
        int N;
        long long K;
        std::cin>>N>>K;
        long long Z[100001];
        for(int i=0;i<N;++i){
            int a,b;
            std::cin>>a>>b;
            Z[a]+=b;
        }
        long long ans=0;
        for(int i=1;i<100001;++i){
            std::cout<<i<<std::endl;
            ans+=Z[i];
            if(ans>=K){
                std::cout<<i<<std::endl;
                return 0;
            }
        }
    }