#include <bits/stdc++.h>
#define endl '\n'
using namespace std;

const int maxN = 100005;

long long n, k, min_diff = INT_MAX, r1, r2;
double points[maxN];

double dist(long long x1, long long y1, long long x2, long long y2)
{
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}

int main()
{
    freopen("ring.in", "r", stdin);
    freopen("ring.out", "w", stdout);

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin>>n>>k;
    for(int i = 0; i < n; i++)
    {
        int x, y;
        cin>>x>>y;

        points[i] = dist(x, y, 0, 0);
        //cout<<points[i]<<" ";
    }
    //cout<<endl;

    sort(points, points + n);

    for(int i = k - 1; i < n; i++)
    {
        long long r11, r22;
        r11 = ceil(points[i]);
        if(ceil(points[i - k + 1]) == floor(points[i - k + 1])) r22 = points[i - k + 1] - 1;
        else r22 = points[i - k + 1];

        if((i != k - 1 && points[i - k] > r22) || (i != n - 1 && points[i + 1] <= r11)) continue;

        if(r11 - r22 < min_diff && r22 != 0 && r11 != 0)
        {
            r1 = r11;
            r2 = r22;
            min_diff = r1 - r2;
        }
    }

    //cout<<r1<<" "<<r2<<endl;
    cout<<r1 * r1 - r2 * r2<<endl;
    return 0;
}