#include <bits/stdc++.h>

#define REP(i, x, n) for(int i = x; i < (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define F first
#define S second
#define mp make_pair

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;

map<char, int> d;

void init() {
  rep(i, 10) {
    d[(char)('0' + i)] = i;
  }
  rep(i, 26) {
    d[(char('A' + i))] = 10 + i;
  }
}

int main() {
  // ios_base::sync_with_stdio(false);
  init();
  
  int N;
  ll ans = -1;
  cin >> N;

  rep(i, N) {
    string v, tmp;
    cin >> v;
    tmp = v;
    
    sort(rall(tmp));
    
    int base = d[tmp[0]] + 1;
    ll num = 0;
    rep(i, v.size()) {
      num = num * base + d[v[i]];
    }
    if(ans == -1 || ans > num) ans = num;
  }
  cout << ans << endl;
  return 0;
}