#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef pair<ll,ll> P;
typedef string str;
typedef vector<P> vp;
typedef vector<string> vs;
typedef vector<bool> vb;

const ll mod=1e9+7;
const ll inf=1e18;

#define rep(i,m,n) for(ll i=m;i<n;i++)
#define repr(i,m,n) for(ll i=m-1;i>=n;i--)
#define fi first
#define se second
#define chmax(x,y) x=max(x,y)
#define chmin(x,y) x=min(x,y)
#define eb(x) emplace_back(x)
#define pb(x) pop_back(x)
#define all(x) x.begin(),x.end()
#define allr(x) x.rbegin(),x.rend()
#define sum(x) accumulate(all(x),0)
#define lb(x,a) lower_bound(all(x),a)
#define ub(x,a) upper_bound(all(x),a)
#define maxe(x,a) max_element(all(x))
#define mine(x,a) min_element(all(x))
#define pc(x) __builtin_popcount(x)
#define gll greater<ll>()



void solve(){
 ll n;
  cin >> n;
  vll a(n);
  rep(i,0,n) cin >> a[i];
  sort(all(a));
  if(a[0]==0) {
   cout << -1 << endl;
   return;
  }
  if(a.back()>=4){
   cout << mod << endl; 
  }
  
  ll ans=1;
  rep(i,0,n){
   ll now=1;
   rep(j,1,a[i]+1) now*=j;
   rep(j,0,now) ans*=a[i]; 
   if(ans>mod) {
     cout << mod << endl;
     return; 
   }
  }
  
  cout << (mod%ans) << endl;
}
int main(){
   cin.tie(nullptr);
  ios::sync_with_stdio(false);
  solve();
}