#include <iostream>
#include <vector>
#include <algorithm>
typedef long long ll;
using namespace std;
const int INF = 2e9;
int main() {
    ios_base::sync_with_stdio(false);

    ll n, K;
    cin >> n >> K;

    vector<ll> v(n);
    for(int i = 0; i < n; i++) {
        cin >> v[i];
    }

    ll L = 0, R = 1e18;

    ll res = -1;
    while(L <= R) {
        ll middle = (L + R) / 2;

        ll zadaci = 0;
        for(int i = 0; i < n; i++) {
            zadaci += middle / v[i];
        }

        if(zadaci >= K) {
            res = middle;
            R = middle - 1;
        }
        else {
            L = middle + 1;
        }
    }

    cout << res << endl;



    return 0;
}