//Normal

#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

void print(auto a){
  cout << a;
}

void prints(auto a){
  cout << a << " ";
}

void prints(){
  cout << " ";
}

void printl(auto a){
  cout << a << endl;
}

void printl(){
  cout << endl;
}

void fix(int n){
  cout << fixed << setprecision(n);
}

int siz(string s){
  return (int)s.size();
}

int main(){
  int N; cin >> N;
  map<string, int> mp;

  for(int i = 0; i < N; i++){
    string S; cin >> S;

    mp[S]++;
  }

  int ans = -1, v = -1;
  for(auto p: mp){
    if(v <= p.second){
      string S = p.first;

      ans = (int)S.size()-2;
      v = p.second;
    }
  }

  printl(ans);

  return 0;
}