#include "bits/stdc++.h"
#define REP(i, n) for(int i = 0; i < int(n); i++)
#define FOR(i,n,m) for(int i = int(n); i < int(m); i++)
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
const int INF = 1e9 + 6;
const ll LLINF = 1e18 + 1;

int f(ll x) {
    if (x < 10) return x;
    int res = 0;
    while (x) {
        res += x % 10;
        x /= 10;
    }
    return f(res);
}

int main() {
    int n;
    cin >> n;
    ll ans = 1;
    REP(i, n) {
        ll p; cin >> p;
        ans *= f(p);
        ans = f(ans);
    }
    cout << ans << endl;
    return 0;
}