#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;
ll mod=1e9+7;

int main() {
    ll N;
    cin>>N;
    vll A(N);
    rep(i,N)cin>>A[i];
    vector<vll> DP(N+1,vll(10,-1e18));
    DP[0][0]=0;
    rep(i,N){
        rep(j,10){
            DP[i+1][j]=max(DP[i][j],DP[i+1][j]);
            DP[i+1][(j+A[i])%10]=max(DP[i][j]+1,DP[i+1][(j+A[i])%10]);
        }
    }
    cout<<DP[N][0]<<endl;
}