#include<bits/stdc++.h>
#define REP(i,n) for(int i=0,i##_len=(n);i<i##_len;++i)
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define All(x) (x).begin(),(x).end()
using namespace std;
using ll = long long;

int main(){
    int N;cin>>N;
    vector<ll> P(N);
    REP(i,N) cin>>P[i];
    vector<vector<int>> p(N,vector<int>(18,0));
    ll lie=0;
    REP(i,N){
        ll q=P[i];
        int j=0;
        while(q){
            lie+=q%10;
            q/=10;
            j++;
        }
    }
    while(lie>=10){
        ll tmp=lie;
        lie=0;
        while(tmp){
            lie+=tmp%10;
            tmp/=10;
        }
    }
    cout<<lie<<endl;
}