#include <bits/stdc++.h>

using namespace std;
using namespace chrono;

#define IOS                  \
    ios::sync_with_stdio(0); \
    cin.tie(0);              \
    cout.tie(0);
//#define int long long
int k;
vector<string> s;
map<vector<int>, int> dp;

int rec(vector<int> levelVector) {
    //base case
    for (int i = 0; i < k; ++i) {
        if (levelVector[i] == s[i].length()) {
            return 0;
        }
    }
    //cache check
    // if(dp[l1][l2]!=-1) return dp[l1][l2];
    if (dp.find(levelVector) != dp.end()) {
        return dp[levelVector];
    }
    //transition
    int ans = 0;
    set<char> st;
    for (int i = 0; i < k; ++i) {
        st.insert(s[i][levelVector[i]]);   //ith strings ith level
        if (st.size() > 1) break;
    }
    if (st.size() == 1) {
        vector<int> temp = levelVector;
        for (int i = 0; i < k; ++i) {
            temp[i]++;  // l1 + 1 , l2 + 1, l3 + 1, ...
        }
        ans = max(ans, 1 + rec(temp));  // ans=1+rec(l1+1,l2+1)
    }
    for (int i = 0; i < k; ++i) {
        vector<int> temp1 = levelVector;
        temp1[i]++;  // l1 + 1 or l2 + 1
        ans = max(ans, rec(temp1));
        temp1[i]--;  // get back to original
    }

    //save and return
    return dp[levelVector] = ans;
}

void solve() {
    cin >> k;
    s.resize(k);
    for (int i = 0; i < k; ++i) {
        cin >> s[i];
    }
    vector<int> temp(k,0);
    cout<<rec(temp)<<endl;
}

signed main() {
#ifndef ONLINE_JUDGE
    freopen("Input.txt", "r", stdin);
    freopen("Output.txt", "w", stdout);
    freopen("Error.txt", "w", stderr);
#endif

    auto start1 = high_resolution_clock::now();

    IOS
    solve();
    auto stop1 = high_resolution_clock::now();
    auto duration = duration_cast<microseconds>(stop1 - start1);
#ifndef ONLINE_JUDGE
    cerr << "Time: " << duration.count() / 1000 << endl;
#endif
    return 0;
}

//input
//5
//abcd
//bcde
//cdea
//abbcde
//aacdeabc

//output
//2