#include <bits/stdc++.h>

#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;

const int INF=1<<29;

int main(){
	int n; scanf("%d",&n);
	vector<int> a(n);
	rep(i,n) scanf("%d",&a[i]);

	vector dp(n+1,vector(10,-INF));
	dp[0][0]=0;
	rep(i,n){
		rep(d,10) dp[i+1][d]=dp[i][d];
		rep(d,10) dp[i+1][(d+a[i])%10]=max(dp[i+1][(d+a[i])%10],dp[i][d]+1);
	}
	printf("%d\n",dp[n][0]);

	return 0;
}