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 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
typedef struct{
    int a,b;
}data;
int cmp(const void *c,const void *d){
    return ((data*)c)->a-((data*)d)->a;
}
int main(void){
    int n,i,k;
    data p[100001];
    scanf("%d %d",&n,&k);
    for(i=0;i<n;i++){
        scanf("%d %d",&p[i].a,&p[i].b);
    }
    qsort(p,n,sizeof(p[0]),cmp);
    for(i=0;i<n;i++){
        k-=p[i].b;
        if(k<=0)break;
    }
    printf("%d\n",p[i].a);
    return 0;
    
}