#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<long long,long long> pll;
#define pb push_back
#define mp make_pair
#define rep(i,n) for(int i=0;i<(n);++i)
constexpr int mod=1000000007;
constexpr int mod1=998244353;
vector<int> dx={0,1,0,-1},dy={-1,0,1,0};
bool inside(int y,int x,int h,int w){
	if(y<h && y>=0 && x<w && x>=0) return true;
	return false;
}


ll calc(ll a){
	ll ret = 0;
	while(a){
		ret += a % 10;
		a /= 10;
	}
	return ret;
}


int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n;cin >> n;
	ll ans = 0;
	rep(i,n){
		ll a;cin >> a;
		ans += calc(a);
	}
	while(ans >= 10){
		ans = calc(ans);
	}
	cout << ans << endl;
}