#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;

int main(){
  int N;
  cin >> N;
  vector<ll> v;
  rep(i,N){
    ll a;
    cin >> a;
    v.push_back(a);
  }

  ll ret = 1;
  rep(i,N){
    ll x = v[i];
    while(x>=10){
      ll t = 0;
      while(x>0){
        t += x % 10;
        x /= 10;
      }
      x = t;
    }
    ret *= x;
    while(ret>=10){
      ll t = 0;
      while(ret>0){
        t += ret % 10;
        ret /= 10;
      }
      ret = t;
    }    
  }

  cout << ret << endl;
  
  return 0;
}