#include<bits/stdc++.h>
using namespace std;

const int N=(1<<20)-1;
int n,a[30],f[N+10],b[30],ans=0;
vector<int>v[30];

bool check(int o){
	for(int i=0;i<31;i++){
		int sum=0;
		for(int j=1;j<=n;j++)if(o&(1<<(j-1)))sum+=v[j][i];
		if(sum>9)return 0;
	}
	return 1;
}

int main(){
	//freopen("b.in","r",stdin);
	freopen("cowescape.in","r",stdin);
	freopen("cowescape.out","w",stdout);
	ios::sync_with_stdio(false);
	cin>>n;
	int M=(1<<n)-1;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		f[1<<(i-1)]=1;
		int x=a[i];
		while(x){
			v[i].push_back(x%10);x/=10;
		}
		while(v[i].size()<31)v[i].push_back(0);
	}
	for(int i=2;i<=M;i++){
		///
		if(check(i))
			for(int j=0;j<n;j++)
				if(i&(1<<j))f[i]=max(f[i],f[i-(1<<j)]+f[1<<j]);
		ans=max(ans,f[i]);
	}
	cout<<ans<<endl;
	return 0;
}