include

include

using namespace std; int main() {

int n, z, big;
bool tag = false;
cin >> n;
for (int i = 0; i < n; i++) {
	cin >> z;
	if (sqrt(z) == int(sqrt(z))) {
		tag = true;
		big = max(z, big);
	}

}
if (tag = true) {
	cout << (sqrt(big));
} else {
	cout << "Not found";
}
return 0；

}