#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;++i)
#define all(x) (x).begin(),(x).end()
using namespace std;
const int INF=1145141919,MOD=1e9+7;
const int64_t LINF=8931145141919364364,LMOD=998244353;
// const int dy[]={0,-1,0,1,1,-1,-1,1};
// const int dx[]={1,0,-1,0,1,1,-1,-1};

int main() {
	int n; cin >> n;
	int64_t k = 1;
	while(n--) {
		int64_t p; cin >> p;
		while(p >= 10) {
			int64_t sum = 0;
			while(p > 0) {
				sum += p % 10;
				p /= 10;
			}
			p = sum;
		}
		k *= p;
		while(k >= 10) {
			int64_t sum = 0;
			while(k > 0) {
				sum += k % 10;
				k /= 10;
			}
			k = sum;
		}
	}
	cout << k << '\n';
	return 0;
}