05- CASIO AND SUPER POWERS

#include<bits/stdc++.h>
 
using namespace std;
 
#define loop(s,e)       for(int i=s; i<=e; i++)
#define ff              first
#define ss              second
#define ld              long double
#define ll              long long int
#define mod             1000000007
#define vll             vector<ll>
#define vi             vector<int>
#define pll             pair<ll, ll>
#define pi             pair<int, int>
#define uom             unordered_map
#define uos             unordered_set
#define mxh             priority_queue<ll>
#define ull             unsigned long long
#define INF             9223372036854775807
#define mnh             priority_queue<ll, vector<ll>, greater<ll>>
#define endl            "\n"
#define Endl            "\n"
#define w(t)            ll tests;    cin>>tests;        while(tests--)
#define pb(x)           push_back(x)
#define ppb()           pop_back()
#define all(x)          x.begin(), x.end()
#define set1(x)         __builtin_popcount(x)
#define mp(a, b)        make_pair(a, b)
#define setp(x, y)      fixed << setprecision(x) << y

void init_code(){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
}

bool isValid(ll mid,vll &v,ll k){
    ll cnt=0;
    for(auto ele:v){
        cnt+=(mid/ele);
    }
    if(cnt>=k) return 1;
    return 0;
}

int main(){
//    init_code();

    ll n,k;cin>>n>>k;
    vll v(n);
    for(ll i=0;i<n;i++) cin>>v[i];
    
    ll lo = 0,hi = v[0]*k;
    ll ans=hi;

    while(lo<=hi){
        ll mid = (hi-lo)/2+lo;
        if(isValid(mid,v,k)){
            ans=mid;
            hi=mid-1;
        }else lo=mid+1;
    }

    cout<<ans<<endl;
    return 0;
}