#include <cstdio>
#include <algorithm>
using namespace std;
struct cow
{
int vote1;
int vote2;
int id;
bool operator < (const cow& A) const
{
return this->vote1 < A.vote1;
}
}
cow[50050];
int main()
{
int n,k;
scanf("%d %d",&n,&k);
for(int i =0 ;i<n;i++)
{
int v1,v2;
scanf("%d %d",&v1,&v2);
cow[i].id=i+1;
cow[i].vote1=v1;
cow[i].vote2=v2;
}
sort(cow,cow+n);
int maxCow=0,maxId=0;
for(int i = n-1;i>=n-k;i--)
{
if(cow[i].vote2>maxCow)
{
maxCow=cow[i].vote2;
maxId=cow[i].id;
}
}
printf("%d",maxId);
}
