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 <stdlib.h>
#include <stdio.h>
#define N 100000
typedef struct{
    int data,kaisu;
}data;
int cmp(const void *a,const void *b){
    return ((data*)a)->data-((data*)b)->data;
}
int main(void){
    data a[N];
    int n,k,i,j,c,d;
    int dat,kai;
    scanf("%d %d",&n,&k);
    for(i=0;i<n;i++){
        scanf("%d %d",&dat,&kai);
        a[i].data=dat;
        a[i].kaisu=kai;
    }
    qsort(a,n,sizeof(data),cmp);
    //for(i=0;i<n;i++)printf("%d %d\n",a[i].data,a[i].kaisu);
    i=0;
    while(1){
        k-=a[i].kaisu;
        if(k<=0)break;
        i++;
    }
    printf("%d\n",a[i].data);
    return 0;
}