bee2832.cpp

/*
 * Contest : Beecrowd
 * Problem : 2832 - Cápsulas
 * Link    : https://judge.beecrowd.com/pt/problems/view/2832
 */

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define fastio ios::sync_with_stdio(0); cin.tie(0);

ll n, f;
vector<ll> cycles;

bool isValid(ll x) {
  ll cnt = 0;
  for (auto c : cycles) cnt += x / c;

  cerr << "mid = " << x << " cnt = " << cnt << "\n";
  return cnt >= f;
}

ll bs() {
  ll l = 1, r = 1e18, m, ans = -1;

  while (l <= r) {
    m = l + (r - l) / 2;

    if (isValid(m)) {
      ans = m;
      r = m - 1;
    }
    else {
      l = m + 1;
    }
  }

  return ans;
}

int main() {
  fastio

  cin >> n >> f;
  cycles.resize(n);
  for (auto &i : cycles) cin >> i;

  cout << bs() << "\n";

  return 0;
}