#include <iostream>
#include <numeric>
#include <cmath>
#include <limits>
#include <stdio.h>
#include <iomanip>
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
using namespace std;
using ll = long long;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
ll Max(ll(a), ll(b), ll(c)) {
	return max(max(a, b), c);
}
ll Min(ll(a), ll(b), ll(c)) {
	return min(min(a, b), c);
}


ll a[100009];


int main() {
	set<ll> A;
	vector<ll> B;
	ll N;
	cin >> N;
	rep(i, N) {
		ll a;
		cin >> a;
		if (A.count(a)) {
			B.push_back(a);
			A.erase(a);
		}
		else {
			A.insert(a);
		}

	}
	if (B.size() < 2) {
		cout << 0 << endl;
		return 0;
	}

	sort(B.begin(), B.end());
	reverse(B.begin(), B.end());
	cout << B.at(0) * B.at(1) << endl;
}
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#pragma GCC optimize("Ofast")
//*********************************************DO IT NOW****************************************************************
#include<bits/stdc++.h> 
#include<random>
#define int long long   
#define pp pair<int,int> 
#define ss second 
#define ff first 
#define pb push_back
#define mod 1000000007
#define pi 3.14159265359
#define mk(arr,n,type)  type *arr=new type[n];
#define sl s1.length();
#define yes cout<< "YES"<<endl
#define no  cout<< "NO"<<endl
#define all(v) (v).begin(),(v).end()
#define s(v)   sort(v,v+n)
#define  mt mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define read(a,n) for(int i=0;i<n;i++)cin>>a[i]
#define print(a,n) for(int i=0;i<n;i++)cout<<a[i]<<" "
#define for1(i,a,n)  for(int i=0;i<n;i++)
#define rep(i, c) for(int i = 0; i < (int)c; i++)
#define set(x) cout<<fixed<<setprecision(x);
using namespace std;
//**********************************************DO IT NO****************************************************************
void fastio()
{  
  #ifndef ONLINE_JUDGE
  freopen("INPUT.txt","r",stdin);
  freopen("OUTPUT.txt","w",stdout); 
  #endif
  ios_base :: sync_with_stdio(false); 
  cin.tie(NULL) ; 
  cout.tie(NULL);
}
int dp[101][1001],ans1=1e9,dp1[1000001];
int num[10];
int a[1000000];
int sum(int n)
{
    int m,s=0;
    while(n)
    {
        m=n%10;
        s+=m;
        n/=10;
    }
    return s;
}
signed main()
{   
    fastio();
    int t=1;
    //cin>>t;
    while(t--)
    {  
        int n;
        cin>>n;
        if(n%(sum(n))==0)
        cout<<"Yes";
        else
        cout<<"No";
    }
}
// 🍪 🍪 🍪
