#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main() {
  int N;
  cin >> N;
  vector<string> v(N);
  int ma = 0;
  for (int i = 0; i < N; ++i) {
    cin >> v[i];
    for (int j = 0; j < v[i].size(); ++j) {
      if (v[i][j] >= '0' && v[i][j] <= '9') {
	ma = max(ma, v[i][j] - '0');
      } else {
	ma = max(ma, v[i][j] - 'A' + 10);
      }
    }
  }

  long long mi = 1e18;
  for (int i = 0; i < N; ++i) {
    ll x = strtol(v[i].c_str(), NULL, ma + 1);
    mi = min(mi, x);
  }
  cout << mi << endl;
  return 0;
}