#include<iostream>
using namespace std;
#include<vector>
#include<string>
#include<algorithm>
#include<map>

const int base[2] = {133, 331};
const int mod[2] = {(int)1e9 + 463, (int)1e9 + 469};

using i64 = long long;

const int N = 1e5 + 1;
vector<i64> power[2];

void init(){
	for(int i = 0; i < 2; ++i){
		power[i].assign(N, 1);
		for(int j = 1; j < N; ++j){
			power[i][j] = power[i][j - 1] * base[i] % mod[i];
		}
	}
	return;
}

pair<int, int> getHash(string s){
	pair<int, int> ans;
	for(int i = 0; i < s.size(); ++i){
		ans.first = (1LL * ans.first * base[0] + s[i]) % mod[0];
		ans.second = (1LL * ans.second * base[1] + s[i]) % mod[1];
	}
	return ans;
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	init();

	int n = 0;
	cin >> n;

	map<pair<int, int>, bool> mp;

	vector<string> s(n);
	for(int i = 0; i < n; ++i){
		cin >> s[i];
	}

	sort(s.begin(), s.end(),
		[&](const string& a, const string& b) {return a.size() < b.size();});

	int answer = 0;
	for(int i = 0; i < n; ++i){
		if(s[i].size() == 1){
			mp[pair<int, int>(s[i][0], s[i][0])] = true;
		}
		else{
			int m = s[i].size();

			pair<int, int> ans;
	        for(int j = 0; j < m - 1; ++j){
		        ans.first = (1LL * ans.first * base[0] + s[i][j]) % mod[0];
				ans.second = (1LL * ans.second * base[1] + s[i][j]) % mod[1];
			}

			int cnt = 0;

			if(mp.find(ans) != mp.end()) cnt++;

			ans.first = (1LL * ans.first * base[0] + s[i][m - 1]) % mod[0];
			ans.second = (1LL * ans.second * base[1] + s[i][m - 1]) % mod[1];

			pair<int, int> a = ans;
			a.first = (a.first - s[i][0] * power[0][m - 1] % mod[0] + mod[0]) % mod[0];
			a.second = (a.second - s[i][0] * power[1][m - 1] % mod[1] + mod[1]) % mod[1]; 

			if(mp.find(a) != mp.end()) ++cnt;

			if(cnt == 2){
				mp[ans] = true;
				answer = max(answer, m);
			}  
		}
	}

	cout << answer << "\n";

	return 0;
}