#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

/*** Typedef ***/
typedef long long ll;
//typedef long long lli;
typedef long long int lli;
typedef unsigned long long ull;
typedef    long double   ld;

//typedef    unordered_set<ll>   usll;
//typedef    unordered_multiset<ll>   umsll;

/*** Loops ***/
#define ffit(i, dat)    for (__typeof(dat.begin()) i = dat.begin(); i != dat.end(); ++i)
#define ff1(i,a,b) for(ll i = a; i < b; i++)
#define ff2(i,a,b) for(ll i = b-1; i >= a; i--)
#define ff3(i,a,b,m) for(ll i = a; i <b; i+=m)
#define ipar(ar,n) ll ar[n]; ff1(i,0,n) cin>>ar[i];
#define opar(ar,n) ff1(i,0,n) cout<<ar[i]<<" ";
#define foRev(num) for(ll i = num - 1; i >= 0; i--)
#define forIn(arr, num) for(ll i = 0; i < num; i++) sc1(arr[i]);
#define forIn1(arr, num) for(ll i = 1; i <= num; i++) sc1(arr[i]);
#define vpnt(ans) for(ll i = 0; i < ans.size(); i++) cout << ans[i] << (i + 1 < ans.size() ? ' ' : '\n');
#define apnt(arr, num) for(ll i = 0; i < num; i++) cout << arr[i] << (i + 1 < num ? ' ' : '\n');

/*** Define Values ***/

#define PI acos(-1.0)
#define eps 1e-7
#define size1 15

/*** STLs ***/
#define cu continue
#define br break
#define rsz resize
#define ins insert
#define ft front
#define bk back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define pb push_back
#define ff first
#define ss second
#define mp make_pair
#define mem(name, value) memset(name, value, sizeof(name))
#define MN3(n1,n2,n3) min(n1,min(n2,n3))
#define MN4(n1,n2,n3,n4) min(n1,min(n2,min(n3,n4)))
#define MX3(n1,n2,n3) max(n1,max(n2,n3))
#define MX4(n1,n2,n3,n4) max(n1,max(n2,max(n3,n4)))
#define mxar(a,n) *max_element(a,a+n)
#define mnar(a,n) *min_element(a,a+n)
#define arr_sm(a,n) accumulate(a,a+n,0)
#define vc_sm(ve,i,j) accumulate(ve.begin()+i,ve.begin()+j+1,0)
#define mx_vc(ve) *max_element(ve.begin(),ve.end())
#define mn_vc(ve) *min_element(ve.begin(),ve.end())
//#define endl " \n"

/*** STLs ***/
typedef vector <ll> vll;
#define vvll vector<vll>
typedef set <ll> sll;
typedef multiset <ll> msll;
//typedef multimap <ll> mpll;
typedef queue <ll> qll;
typedef map <ll, ll> mll;
typedef pair <ll, ll> pll;
typedef vector <pair <ll, ll> > vpll;
typedef priority_queue <pair <ll, ll> > pqpll;
#define ml unordered_map<ll,ll>
///typedef    unordered_multiset<int>   umsi;
typedef    unordered_set<ll>   us;
#define    oncnt    __builtin_popcount
#define    zerobegin   __builtin_clz
#define    zeroend   __builtin_ctz
#define    parity   __builtin_parity

///vector<vector<int>> v(10, vector<int>(20,500)); 2d vector initialization. of 10 rows and 20 columns, with value 500.

/*** Sorts ***/
#define all(v) (v).begin(), (v).end()
#define rev(v) reverse(all(v))
#define srt(v) sort(all(v))
#define srtgrt(v) sort(all(v), greater<ll>())
#define prsrt greater<pair<int,int>>()
/*** Some Prints ***/
#define ip(n) ll n; cin>>n;
#define ip2(n,k) ll n; cin>>n; ll k; cin>>k;
#define kl    '\n'
#define no cout << "NO" << '\n'
#define yes cout << "YES" << '\n'
#define case cout << "Case " << t++ << ": ";
#define ps(x,y)         fixed<<setprecision(y)<<x
#define inf             1e18
#define dbg(x) cout << '>' << #x << ':' << x << endl;
#define w(x)             ll x; cin>>x; while(x--)
bool isPtSquare(long double x)
{
    long double sr = sqrt(x);
    return ((sr - floor(sr)) == 0);
}
/*
ll fact(ll n,ll mod)
{
	ll prod=1;
	for(ll i=1;i<=n;i++)
	{
		prod=(prod*i)%mod;
	}
	return prod;
}
ll fac[500001];
void calc_fac(ll mod)
{
	fac[0]=1;
	for(int i=1;i<=500000;i++)
	{
		fac[i]=(fac[i-1]*i)%mod;
	}
}
ll comb(ll n,ll r,ll mod)
{
	if(r>n)
	{
		return 0;
	}
	ll ans=fac[n];
	ll den=(fac[n-r]*fac[r])%mod;
	ans=(ans*fast_power(den,mod-2,mod))%mod;
	return ans;
}
bool isvwl(char ch) {
    if(ch=='a' || ch=='e' || ch=='i' || ch=='o' || ch=='u')
         return true;
    else return false;
}
lli power(lli b, lli p, lli m = mod){
    lli res = 1;
    while(p > 0){
        if(p & 1){
            res = (res * b) % m;
        }
        b = (b * b) % m;
        p = p>>1;
    }
    return res;
}

lli modInverse(lli n, lli m = mod){
    return power(n, m - 2, m);
}

bool mySort(pair<int, int> p1, pair<int, int> p2){
    if(p1.se < p2.se){
        return true;
    }
    else if(p1.se == p2.se and p1.fi < p2.fi){
        return true;
    }
    return false;
}

vector<lli> primes;

vector<lli> sieve(lli n){ // find all prime numbers <= n
    vector<bool> v(n + 1, false);
    v[2] = true;
    for(int i = 3; i <= n; i += 2){
        v[i] = true;
    }
    for(size_t i = 3; i <= n; i += 2){
        if(v[i]){
            for(size_t j = i * i; j <= n; j += 2 * i){
                v[j] = false;
            }
        }
    }
    v[1] = false;
    v[0] = false;
    for(int i = 0; i < v.size(); i++){
        if(v[i]){
            primes.push_back(i);
        }
    }
    return primes;
}

lli gcd(lli a, lli b){
    while(b > 0){
        lli r = a % b;
        a = b;
        b = r;
    }
    return a;
}

lli lcm(lli a, lli b){
    lli g = gcd(a, b);
    return (a * b) / g;
}

vector<pll> primeFactors(lli n){ // returns all prime factors with along with their powers
    lli p = primes[0];
    vector<pll> f;
    int i = 0;
    while(i < primes.size() && p * p <= n){
        lli count = 0;
        while(p > 0 and n % p == 0){
            count++;
            n /= p;
        }
        if(count > 0){
            f.push_back(mp(p, count));
        }
        i++;
        if(i == primes.size()){
            break;
        }
        p = primes[i];
    }
    if(n > 1){ // number is itself prime
        f.push_back(mp(n, 1));
    }
    return f;
}

vector<lli> factors(lli n){ // returns all factors of a given number
    lli lim = sqrt(n);
    vector<lli> f;
    for(int i = 1; i <= lim; i++){
        if(n % i == 0){
            f.push_back(i);
            f.push_back(n / i);
            if(i*i == n){
                f.pop_back();
            }
        }
    }
    return f;
}

lli ceilAB(lli a, lli b){
    return (a + b - 1) / b;
}
ll bigmod(ll n,ll pow)
{
    if(pow==0)
        return 1;
    if(pow==1)
        return n%mod;

    ll ans=bigmod(n,pow/2);
    ans=(ans*ans)%mod;

    if(pow%2==1)
    {
        ans=(ans*n)%mod;
    }
    return ans%mod;
}
ll fact[1000005];

ll nCr(ll n,ll r)
{

    ll ans=fact[n];
    ans=(ans*bigmod(fact[r],mod-2))%mod;
    ans=(ans*bigmod(fact[n-r],mod-2))%mod;
    return ans;
}
ll binpow(ll a, ll b, ll mod = 2e18){
	ll ans = 1;
	while(b){
		if(b&1) ans*=a;
		a*=a;
		ans%=mod;
		a%=mod;
		b/=2;
	}
	return ans;
}
const int mxn = 1e3;

ll fact[mxn + 1];
void calcfac(ll n, ll mod = 2e18){
	fact[0]  = 1;
	for(int i = 1; i<=n;++i){
		fact[i] = fact[i-1]*i;
		fact[i] %= mod;
	}
}

ll nCr(ll p, ll q, ll mod = 2e18){
	ll val = fact[p];
	ll invfact = fact[q]*fact[p-q];
	val%=mod;
	invfact%=mod;
	val*=binpow(invfact, mod - 2, mod);
	return val%mod;
}


ll nPr(ll p, ll q, ll mod = 2e18){
	ll val = nCr(p, q, mod);
	val*=fact[q];
	val%=mod;
	return val;
}
*/
bool isprime(int n)
{
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;
    if (n % 2 == 0 || n % 3 == 0)
        return false;
    for (int i = 5; i * i <= n; i += 6)
    {
        if ((n % i == 0) || (n % (i + 2) == 0))
            return false;
    }
    return true;
}
ll power(ll x, ll y)
{
    ll temp;
    if(y == 0)
        return 1;
    temp = power(x, y / 2);
    if (y % 2 == 0)
        return temp * temp;
    else
    {
        if(y > 0)
            return (x * temp * temp);
        else
            return ((temp * temp) / x);
    }
}
//#define mod 10000007

//ll pmod(ll a,ll b){ll res=1;a%=mod;assert(b>=0);for(; b; b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
//ll expo(ll x, ll y){ ll res = 1; x = x % mod;  while (y > 0) { if (y & 1)res = (res*x) % mod; y = y>>1;x = (x*x) % mod;}return res;}
//void matmul(ll a[][2], ll b[][2]) { ll tmp[2][2]; for(int i=0; i<2; i++) { for(int j=0; j<2; j++) { tmp[i][j] = 0; for(int k=0; k<2; k++) tmp[i][j] = (tmp[i][j] + a[i][k]*b[k][j]) % mod; }} for(int i=0; i<2; i++) for(int j=0; j<2; j++) a[i][j] = tmp[i][j]; }
//ll fibo(int n)    // returns nth fibonacci number, also S(n) = f(n+2)-1
//{ if(n == 0) return 0; else if(n == 1) return 1; ll T[2][2] = { {0, 1} , {1, 1} }; ll res[2][2] = { {1, 0}, {0,1} }; n--; while(n) { if(n & 1) matmul(res, T); n >>= 1; matmul(T, T); } return res[1][1]; }

#define go(i, a) for (auto i : a)
#define go1(it, v) for(auto it = v.begin(); it != v.end(); ++it)
#define mk(arr,n,type) type *arr=new type[n];
#define sz(obj) (int(obj.size()))
#define ipve(vc,n) vll vc(n); ff1(i,0,n){cin>>vc[i];}
#define ipvc(vc,n) vll vc; ff1(i,0,n){ip(x);vc.pb(x);}
bool sortbysec(const pair<pair<ll,ll>,ll> &a,const pair<pair<ll,ll>,ll> &b)
{
    return (a.second < b.second);
}
bool cmp(pll a,pll b)
{
    return a.ff - a.ss < b.ff - b.ss;
}
bool p2(ll n)
{
    if(n==0)
        return false;

    return (ceil(log2(n)) == floor(log2(n)));
}

const ll N = 2e5+10;
//const ll N = 10000;
const ll mod=1e9+7;
//bool ans = all_of(arr, arr + 6, [](int x) {return x & 1; } );
const double pi = 3.141592653589793238460;
ll c(ll n,ll m)
{
    ll sm = 1;
    ff1(i,1,m+1)
    {
        sm*=(n-i+1);
        sm/=i;
    }
    return sm;
}
//string a="cdefghijklmnopqrstuvwxyz";
ld f(ld n)
{
    ld sm = 1;
    ff1(i,1,n+1)
    {
        sm*=i;
    }
    return sm;
}
ld pc(ld n, ld k)
{
    ld sm = f(n)/f(n-k);
    return sm;
}

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

	long long o;
	ip(n);
	o=1;
	ipvc(a,n);
	srt(a);
	for(int i=0;i<n;i++){
		if((__int128)o*a[i]>1000000000000000000LL){
			cout<<-1;
			return 0;
		}
		o*=a[i];
	}
	cout<<o;
    return 0;
}


Measured memory_bytes: 4208