#include<bits/stdc++.h>
using namespace std;
int main(){
    long n;
    cin >> n;
    long a[n];
    for(int i=0;i<n;i++)cin >> a[i];
    vector<vector<long> >dp(n+1,vector<long>(10,-1<<30));
    dp[0][0] = 0;
    for(int i=0;i<n;i++){
        for(int j=0;j<10;j++){
            dp[i+1][(j+a[i])%10] = max(dp[i][j]+1,dp[i][(j+a[i])%10]);
        }
    }
    cout << dp[n][0]<<endl;
}