#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("YES");}else{puts("NO");}
#define MAX_N 200005

int main() {
    int n; cin >> n;
    int f[10] = {};
    rep(i,n){
        int a;
        cin >> a;
        f[a%10]++;
    }
    int dp[10] = {};
    srep(i,1,10) dp[i] = -1001001001;
    rep(x,10){
        rep(_,f[x]){
            int dp2[10];
            rep(i,10) dp2[i] = dp[i];
            rep(i,10){
                dp2[i] = max(dp2[(i+x)%10], dp[i] + 1);
            }
            rep(i,10) dp[i] = dp2[i];
        }
    }
    cout << dp[0] << endl;
    return 0;
}