/*
Time:2019.12.3
Author: Goven
type：排序 
err:
ref:
*/
#include<iostream>
#include<algorithm>
using namespace std;

struct Vote{
    int a, b;
    int idx;
};

Vote cows[50005];

bool cmpa(const Vote &x, const Vote &y) {
    return x.a > y.a;
}

bool cmpb(const Vote &x, const Vote &y) {
    return x.b > y.b;
}

int main()
{
    int n, k;
    cin >> n >> k;
    for (int i = 0; i < n; i++) {
        cin >> cows[i].a >> cows[i].b;
        cows[i].idx = i;
    }
    sort(cows, cows + n, cmpa);
    sort(cows, cows + k, cmpb);
    cout << cows[0].idx + 1 << endl;
    return 0;
}