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>
int main(){
int N,K,i,j,s,t;
int a[100001];
int b[100001];
scanf("%d %d",&N,&K);
for(i=0;i<N;i++){
scanf("%d %d",&a[i],&b[i]);
}
for(i=0;i<K;i+=b[s]){
s=100000;
  for(j=0;j<N;j++){
    if(a[j]<s){
    t=j;
    s=a[t];
    }
  }
  if(K<=(i+b[t])){
  printf("%d\n",s);
  return 0;
  }
a[s]=100001;
}
printf("%d\n",s);
return 0; 
}