#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define MAXN 50010
using namespace std;
int n,m;
struct nond
{
    int x,y,id;
}
v[MAXN];
int cmp(nond a,nond b)
{
    return a.x>b.x;
}
int cmp1(nond a,nond b)
{
    return a.y>b.y;
}
int Main()
{
    freopen("elect.in","r",stdin);
    freopen("elect.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
    scanf("%d%d",&v[i].x,&v[i].y),v[i].id=i;
    sort(v+1,v+1+n,cmp);
    sort(v+1,v+1+m,cmp1);
    cout<<v[1].id;
}
int haha=Main();
int main(){;}