#include #include #include #include #include #define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define FOR(i,m,n) for(int i=(m);i<(n);++i) #define REP(i,n) FOR(i,0,n) #define ALL(v) (v).begin(),(v).end() const int INF = 0x3f3f3f3f; const long long LINF = 0x3f3f3f3f3f3f3f3fLL; const double EPS = 1e-8; const int MOD = 1000000007; // const int MOD = 998244353; const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1}; // const int dy[] = {1, 1, 0, -1, -1, -1, 0, 1}, // dx[] = {0, -1, -1, -1, 0, 1, 1, 1}; struct IOSetup { IOSetup() { cin.tie(nullptr); ios_base::sync_with_stdio(false); cout << fixed << setprecision(20); cerr << fixed << setprecision(10); } } iosetup; /*-------------------------------------------------*/ int main() { int n; cin >> n; long long ans = 1; while (n--) { long long p; cin >> p; while (p >= 10) { long long tmp = 0; while (p > 0) { tmp += p % 10; p /= 10; } p = tmp; } ans *= p; } while (ans >= 10) { long long tmp = 0; while (ans > 0) { tmp += ans % 10; ans /= 10; } ans = tmp; } cout << ans << '\n'; return 0; }