C++ :

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

int n, m, a[100001];
long long l = 0, r = 1e18, mid, ans = 1e18, cnt;

int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        cin >> a[i];

    while (l <= r) {
        mid = (l + r) / 2;
        cnt = 0;
        for (int i = 1; i <= n; i++)
            cnt += (mid / a[i]);

        if (cnt < m)
            l = mid + 1;
        else {
            ans = min(ans, mid);
            r = mid - 1;
        }
    }

    cout << ans;
    return 0;
}