#include<bits/stdc++.h> 
using namespace std;
int n,m;
struct luo{
    int x,y,id;
}v[50005];
int cmp1(luo a,luo b)
{
    return a.x>b.x;
}
int cmp2(luo a,luo b)
{
    return a.y>b.y;
}
int main()
{
    freopen("elect.in","r",stdin);
    freopen("elect.out","w",stdout);
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        cin>>v[i].x>>v[i].y;
		v[i].id=i;
	}
    sort(v+1,v+1+n,cmp1);
    sort(v+1,v+1+m,cmp2);
    cout<<v[1].id;
    return 0;
}