#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define li long
#define ll long long
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pli pair<li,li>
#define pll pair<ll,ll>
#define pb push_back
#define fori(i,k,n) for(int i = k;i<n; i++)
#define rfori(i,k,n) for(int i = k; i>=n; i--)
#define tc int t;cin>>t;while(t--)
#define all(v) v.begin(),v.end()
#define inf INT_MAX
#define ninf INT_MIN
#define W(x) cout<<x<<endl
#define WW(x,y) cout<<x<<' '<<y<<endl;
#define in(x) cin>>x
#define int long long
const ll mod = 998244353;
const ll mod2 = 1e9+7;
template <class T>
using oset = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;

void fastio()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
} 
template<class T>
T power(T a,T b){
    T res = (T)1;
    while(b>0){
        if(b&1)res = res*a;
        b>>=1;
        a*=a;
    }
    return res;
}
struct Node{
    int first;int second;
    Node(int x,int y){
        this->first = x;
        this->second = y;
    }
};
struct comparator{
    bool operator()(const Node &a,const Node &b){
        int lena = a.second-a.first+1;
        int lenb = b.second-b.first+1;
        if(lena == lenb)return a.first<b.first;
        else return lena>lenb;
    }
};
ll power(ll x,ll y,ll mod){
    ll res = 1;
    x%=mod;
    while(y>0){
        if(y&1)res = (res*x)%mod;
        y>>=1;
        x = (x*x)%mod;
    }
    return res;
}
const int mxn = 1e18;
signed main(){
    int n;
    cin>>n;
    vector<int> a(n);
    set<int> st;
    for(int i = 0; i<n; i++){
        cin>>a[i];
        st.insert(a[i]);
    }
    sort(all(a));
    if(st.find(0)!=st.end())return cout<<0,0;
    int ans = 1;
    for(int i = 0; i<n; i++){
        ans*=a[i];
        if(ans%mxn!=ans||ans%mxn!=0){
            ans = -1;
            break;
        }
    }
    cout<<ans<<"\n";
}