#include <bits/stdc++.h>
using namespace std;
#define int long long
const long double PI = 3.14159265359;
void solve()
{
int n;
cin >> n;
vector<int> arr(n);
for (auto &val : arr)
cin >> val;
if (count(arr.begin(), arr.end(), 9) == 0)
cout << -1 << '\n';
else
cout << *min_element(arr.begin(), arr.end()) << '\n';
}
signed main(void)
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
if (fopen("input.txt", "r"))
{
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
}
int t = 1;
// cin >> t;
while (t--)
{
solve();
}
return 0;
}
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