#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000



int main(){

	int N;
	cin>>N;
	
	vector<int> A(N);
	rep(i,N){
		cin>>A[i];
		A[i] %= 10;
	}
	
	vector dp(N+1,vector<int>(10,-Inf));

	dp[0][0] = 0;
	
	rep(i,N){
		rep(j,10){
			if(dp[i][j]==-Inf)continue;
			dp[i+1][j] = max(dp[i+1][j],dp[i][j]);
			int nj = j + A[i];
			nj %= 10;
			dp[i+1][nj] = max(dp[i+1][nj],dp[i][j]+1);
		}
	}
	
	cout<<dp.back()[0]<<endl;

	return 0;
}