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 <math.h>

#define rep(i, n) for(int i = 0; i < n; i++)
#define in_arr(type, a, n) for(int i = 0; i < n; i++) scanf(type, &((a)[i]));
#define ll long long int

int main(){
    int n;
    ll k;
    scanf("%d%lld", &n, &k);
    int a[n], b[n];
    rep(i, n) scanf("%d%d", &a[i], &b[i]);
    rep(i, n){
        if(b[i] < k) {
            k -= b[i];
            continue;
        }
        printf("%d", a[i]);
        break;
    }
    return 0;
}