#include <bits/stdc++.h>
#define maxn 1000007
#define int long long
#define ull unsigned long long
#define mod 233333333
using namespace std;
int base1 = 133, base2 = 233;
inline int pls(int a, int b) {int m = a + b; return m < mod ? m : m - mod;}
inline int dec(int a, int b) {int m = a - b; return m < 0 ? m + mod : m;}
inline int mul(int a, int b) {return 1ll * a * b % mod;}
inline int fpow(int a, int b) {
  int ans = 1;
  for(; b; b >>= 1,a = mul(a, a)) if(b & 1) ans = mul(ans, a);
  return ans;
}
inline int inv(int a) {return fpow(a, mod - 2);}
inline int dvi(int a, int b) {return mul(a, inv(b));};
inline int qread() {
  char c = getchar(); int num = 0, f = 1;
  for(; !isdigit(c); c=getchar()) if(c == '-') f = -1;
  for(; isdigit(c); c=getchar()) num = num * 10 + c - '0';
  return num * f;
}
char s[maxn];
ull p1[maxn];
int p2[maxn];
vector<ull> hash1[maxn];
vector<int> hash2[maxn];
int len[maxn];
map<ull, bool> mp1;
map<int, bool> mp2;
inline ull get_hash1(int i, int l, int r) {
  return hash1[i][r] - hash1[i][l - 1] * p1[r - l + 1];
}
inline int get_hash2(int i, int l, int r) {
  return dec(hash2[i][r], mul(hash2[i][l - 1], p2[r - l + 1]));
}
int ans = 0;
map<int, map<ull, int>> mem;
signed main() {
  int n = qread();
  p1[0] = p2[0] = 1;
  for(int i = 1; i <= 1e5; ++i) p1[i] = p1[i - 1] * base1;
  for(int i = 1; i <= 1e5; ++i) p2[i] = mul(p2[i - 1], base2); 
  for(int i = 1; i <= n; ++i) {
    scanf("%s", s + 1);
    hash1[i].push_back(0);
    hash2[i].push_back(0);
    int m = strlen(s + 1);
    len[i] = m;
    for(int j = 1; j <= m; ++j) {
      hash1[i].push_back(0);
      hash2[i].push_back(0);
      hash1[i][j] = hash1[i][j - 1] * base1 + s[j];
      hash2[i][j] = pls(s[j], mul(hash2[i][j - 1], base2));
    }
    mem[hash2[i][m]][hash1[i][m]] = 1;
    mp1[hash1[i][m]] = 1;
    mp2[hash2[i][m]] = 1;
    
//    cout << hash2[i][m] << '\n';
  }
  //cout << get_hash2(4, 2, 2) << '\n';
  for(int i = 1; i <= n; ++i) {
    if(len[i] >= 500) continue;
    bool f = 0;
    for(int l = 1; l <= len[i]; ++l) {
      for(int r = l; r <= len[i]; ++r) {
        int o1 = get_hash1(i, l, r);
        int o2 = get_hash2(i, l, r);
        if(!mem[o2][o1]) {
          f = 1;
          break;
        }
      }
      if(f) break;
    }
    if(!f) ans = max(ans, len[i]);
  }
  cout << ans << '\n';
  return 0;
}