#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <algorithm>
#include <cmath>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <bitset>
#include <sstream>
#include <cstdlib>
#include <cstdio>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <climits>
#include <ctype.h>
#include <ctime>
using namespace std;

#define PI acos(-1.0)
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define fi first
#define se second
#define si(x) scanf("%d", &(x))

#define eps 1e-8
#define mod 1000000007

typedef long double ld;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<vector<int>> vvi;

struct Matrix {
    vvi data;
    int r, c;
    Matrix(int row, int col, bool identity = false) : r(row), c(col) {
        data.assign(row, vector<int>(col, 0));
        if (identity) {
            for (int i = 0; i < r; ++i) {
                data[i][i] = 1;
            }
        }
    }
    Matrix operator * (Matrix& other) {
        int m = r, n = c, p = other.c;
        Matrix res(m, p);
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < p; ++j) {
                for (int k = 0; k < n; ++k) {
                    res.data[i][j] += data[i][k] * other.data[k][j];
                }
            }
        }
        return res;
    }
};

// 扩展欧几里得算法 res[1] * a + res[2] * b = res[0] = gcd(a, b)
vector<int> extendGcd(int a, int b) {
    if (b == 0) {
        return {a, 1, 0};
    } else {
        vector<int> tmp = extendGcd(b, a % b);
        return {tmp[0], tmp[2], tmp[1] - (a / b) * tmp[2]};
    }
}

// 矩阵快速幂
Matrix matrix_power(Matrix base, ll exp) {
    int n = base.r;
    Matrix res(n, n, true);
    while (exp) {
        if (exp & 1) {
            res = res * base;
        }
        base = base * base;
        exp >>= 1;
    }
    return res;
}

// 带模快速幂
template <typename T>
T power_mod(T base, int exp) {
    T res = 1;
    while (exp) {
        if (exp & 1) res = res * base % mod;
        base = base * base % mod;
        exp >>= 1;
    }
    return res;
}

// 快速幂
template <typename T>
T power(T base, int exp) {
    T res = 1;
    while (exp) {
        if (exp & 1) res *= base;
        base *= base;
        exp >>= 1;
    }
    return res;
}

// 求逆元
ll inv(ll a) {
    return power_mod(a, mod - 2);
}

#define MAXFAC 100010

ll fac[MAXFAC];

void initFac() {
    fac[0] = 1;
    for (int i = 1; i < MAXFAC; ++i) {
        fac[i] = i * fac[i - 1] % mod;
    }
}

ll Combine(ll a, ll b) {
    return (fac[a] * inv(fac[b]) % mod) * inv(fac[a - b]) % mod;
}

/******************************** template ********************************/
#define MAXN 55
int n, k;
int x[MAXN], y[MAXN];
vector<int> xx, yy;

unordered_map<int, int> mapx, mapy;

int bit[MAXN][MAXN];

int lowbit(int x) {return x & -x;}

void add(int p, int q, int v) {
    for (int i = p; i < MAXN; i += lowbit(i)) {
        for (int j = q; j < MAXN; j += lowbit(j)) {
            bit[i][j] += v;
        }
    }
}

int sum(int p, int q) {
    int res = 0;
    for (int i = p; i; i -= lowbit(i)) {
        for (int j = q; j; j -= lowbit(j)) {
            res += bit[i][j];
        }
    }
    return res;
}

int range(int x1, int y1, int x2, int y2) {
    int res = sum(x2, y2) - sum(x2, y1 - 1) - sum(x1 - 1, y2) + sum(x1 - 1, y1 - 1);
    return res;
}

int main() {
    cin >> n >> k;
    for (int i = 0; i < n; ++i) {
        scanf("%d%d", x + i, y + i);
        xx.pb(x[i]);
        yy.pb(y[i]);
    }
    sort(all(xx));
    sort(all(yy));
    xx.resize(distance(xx.begin(), unique(all(xx))));
    yy.resize(distance(yy.begin(), unique(all(yy))));

    memset(bit, 0, sizeof(bit));
    for (int i = 0; i < n; ++i) {
        int ind = lower_bound(all(xx), x[i]) - xx.begin() + 1;
        mapx[ind] = x[i];
        x[i] = ind;
        ind = lower_bound(all(yy), y[i]) - yy.begin() + 1;
        mapy[ind] = y[i];
        y[i] = ind;
        add(x[i], y[i], 1);
    }

    ll res = LLONG_MAX;
    for (int l = 0; l < xx.size(); ++l) {
        for (int r = l; r < xx.size(); ++r) {
            for (int d = 0; d < yy.size(); ++d) {
                for (int u = d; u < yy.size(); ++u) {
                    if (range(l + 1, d + 1, r + 1, u + 1) >= k) {
                        res = min(res, 1LL * (mapx[r + 1] - mapx[l + 1]) * (mapy[u + 1] - mapy[d + 1]));
                    }
                }
            }
        }
    }
    cout << res;

    return 0;
}

Measured memory_bytes: 256