#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); i ++)
using namespace std;
typedef long long ll;
typedef pair<ll,ll> PL;
typedef pair<int,int> P;
const int INF = 1e9;
const ll MOD = 1e9 + 7;
const vector<int> dy = {-1,0,1,0};
const vector<int> dx = {0,1,0,-1};

int digitsum(ll n) {
    int ans = 0;
    ll power = 10;
    while (n > 0) {
        ans += n%power;
        n /= power;
    }
    return ans;
}

int main() {
    int n; cin >> n;
    int ans = 1;
    rep(_,n) {
        ll p; cin >> p;
        int p2 = digitsum(p);
        ans *= p2;
        while (ans/10 > 0) {
            ans = digitsum(ans);
        }   
    }
    printf("%d",ans);
    printf("\n");
}