#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	int N;
	cin >> N;
	int cnt[10];
	vector<int> A(N);
	REP(i, N) scanf("%d", &A[i]);
	int dp[10];
	memset(dp, -1, sizeof(dp));
	dp[0] = 0;
	REP(i, N) {
		const int cur = i & 1, nex = cur ^ 1;
		int ndp[10];
		memset(ndp, -1, sizeof(ndp));
		REP(j, 10) if (~dp[j]) chmax(ndp[(j + A[i]) % 10], dp[j] + 1);
		REP(j, 10) chmax(dp[j], ndp[j]);
	}
	cout << dp[0] << endl;
}