#include <cstdio>
#include <cassert>
#include <climits>
#include <set>
#include <queue>
#include <vector>
#include <utility>
#include <algorithm>
using std::set;
using std::pair;
using std::vector;
using std::priority_queue;

int n, k;
struct Cell {
  Cell(int id) : id(id) {}
  void Input() { assert(scanf("%d%d", &a, &b) == 2); }
  int id, a, b;
};
vector<Cell> board;

bool CellCompare(const Cell &x, const Cell &y) {
  return x.a < y.a;
}

void Init() {
  assert(scanf("%d%d", &n, &k) == 2);
  for (int i = 1; i <= n; ++i) {
    Cell cell(i);
    cell.Input();
    board.push_back(cell);
  }
}

void Work() {
  // Sort the cells by the order of A_i
  std::sort(board.begin(), board.end(), CellCompare);
  set<int> used;
  used.insert(0);
  used.insert(n + 1);
  priority_queue< pair<int, int> > queue;
  int ans = INT_MAX;
  int gap_cnt = 1;
  for (const Cell &cell : board) {
    // Insert the cells one by one and try to remove the cells with largest B_i
    if (gap_cnt) {
      auto rit = used.lower_bound(cell.id);
      auto lit = rit; --lit;
      if (*rit - *lit > k) --gap_cnt;
      auto it = used.insert(cell.id).first;
      lit = it; --lit;
      rit = it; ++rit;
      if (*it - *lit > k) ++gap_cnt;
      if (*rit - *it > k) ++gap_cnt;
      queue.push({cell.b, cell.id});
    } else if (queue.top().first >= cell.b) {
      used.insert(cell.id);
      queue.push({cell.b, cell.id});
    }
    if (gap_cnt) continue;
    while (!queue.empty()) {
      int id = queue.top().second;
      auto it = used.find(id);
      auto lit = it; --lit;
      auto rit = it; ++rit;
      if (*rit - *lit <= k) {
        used.erase(it);
        queue.pop();
      } else {
        break;
      }
    }
    ans = std::min(ans, queue.top().first * cell.a);
  }
  printf("%d\n", ans);
}

int main() {
  Init();
  Work();
  return 0;
}