usaco nov2k11silver2

#define _CRT_SECURE_NO_WARNINGS
#pragma comment(linker, "/STACK:256000000")

#include <bits/stdc++.h>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef pair<string, int> psi;
typedef vector<string> vs;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<char> vc;
typedef vector<pii> vpii;
typedef vector<pair<ll, ll> > vpll;
typedef long double ld;

#define forn(i, n) for (int i = 0; i < (int)n; i++)
#define for1(i, n) for (int i = 1; i <= (int)n; i++)
#define forq(i, s, t) for (int i = s; i <= t; i++)
#define ford(i, s, t) for (int i = s; i >= t; i--)
#define mk make_pair
#define inb push_back
#define outb pop_back
#define all(v) v.begin(), v.end()
#define X first
#define Y second
#define TIME clock() * 1.0 / CLOCKS_PER_SEC
#define sqr(x) (x) * (x)
#define y1 amdknkgsdaasdwapgnpikn
//
#define mp make_pair
#define pb push_back
#define XX first
#define YY second
//

const ld EPS = 1e-9;
const ld pi = acos(-1.0);

const int MAXN = (int)1e5 + 7;
const int INF = (int)2e9;
const ll LINF = (ll)7e18;
const ll MOD = (ll)1e9 + 7;
const int CHASH = (ll)239017;
const ld DINF = (ld)1000000000000000.0;

int n, d;
pii a[MAXN];

int solve()
{
    scanf("%d %d", &n, &d);
    forn(i, n)
        scanf("%d %d", &a[i].X, &a[i].Y);
    sort(a, a + n);
    set<pii> q;
    ll ans = 0;
    int r = 1;
    forn(i, n)
    {
        q.erase(mk(a[i].Y, i));
        while (r < n && a[i].X + d < a[r].X)
        {
            q.insert(a[r]);
            ++r;
        }
        --r;
        set<pii>::iterator itl = q.upper_bound(mk(a[i].Y - d, INF));
        set<pii>::iterator ritr = q.lower_bound(mk(a[i].Y + d, -1));
        ++ritr;
        pii lt = (*itl);
        if (ritr == q.begin())
            continue;
        --ritr;
        pii rt = (*ritr);
        if (lt.Y != rt.Y && lt.X > a[i].Y - d && lt.X < a[i].Y + d && rt.X > a[i].Y - d && rt.X < a[i].Y + d)
            puts("-1"), exit(0);
        if (rt.X > a[i].Y - d && rt.X < a[i].Y + d)
        {
            if (ans)
                puts("-1"), exit(0);
            pii Q = a[rt.Y];
            ans = abs(Q.X - a[i].X) * abs(Q.Y - a[i].Y);
        }
        else
        {
            if (lt.X > a[i].Y - d && lt.X < a[i].Y + d)
            {
                if (ans)
                    puts("-1"), exit(0);
                pii Q = a[lt.Y];
                ans = abs(Q.X - a[i].X) * abs(Q.Y - a[i].Y);
            }
        }
    }
    printf("%lld", ans);
    return 0;
}

int main()
{
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    solve();
    return 0;
}