#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;


int main(){
  int N;
  cin >> N;
  vector<ll> v;
  rep(i,N){
    ll a;
    cin >> a;
    v.push_back(a);
  }

  map<ll,int> memo;
  memo[v[0]] = 1;
  REP(i,1,N){
    map<ll,int> tmp;
    FOR(it,memo){
      //+
      tmp[it->first + v[i]] = 1;
      //-
      tmp[it->first - v[i]] = 1;
      //*
      tmp[it->first * v[i]] = 1;
      //div
      if(v[i]!=0){
        tmp[it->first / v[i]] = 1;
      }
    }
    memo = tmp;
  }

  ll mx = -1000000000000000000LL;
  FOR(it,memo){
    mx = max(mx, it->first);
  }
  cout << mx << endl;
  
  return 0;
}