#include <string>
#include <iostream>
#include <set>
#include <vector>
#include <algorithm>
#include <random>

using namespace std;
using ll = long long;
using hash_t = unsigned long long;

hash_t BASE = 131;

int main() {
    mt19937_64 rng(random_device{}());
    BASE = rng() | 1;

    int n;
    cin >> n;

    int ans = 0;
    set<hash_t> perfect;
    vector<string> str(n);
    for (int i = 0; i < n; i++) {
        cin >> str[i];
    }
    sort(str.begin(), str.end(), [&](auto &lhs, auto &rhs) {
        return lhs.size() < rhs.size();
    });
    for (auto &s : str) {
        if (s.size() == 1) {
            perfect.insert(s[0]);
            ans = max(ans, 1);
            continue;
        }
        hash_t hash0 = 0, hash1 = s[0];
        for (int i = 1; i < (int)s.size() - 1; i++) {
            hash0 = hash0 * BASE + s[i];
            hash1 = hash1 * BASE + s[i];
        }
        hash0 = hash0 * BASE + s[s.size() - 1];
        hash_t hash2 = hash1 * BASE + s[s.size() - 1];
        if (perfect.count(hash0) && perfect.count(hash1)) {
            perfect.insert(hash2);
            ans = max(ans, (int)s.size());
        }
    }

    cout << ans << endl;

    return 0;
}