import math._

object Main {
  def main(args: Array[String]) {
    val sc = new java.util.Scanner(System.in)
    val n = sc.nextInt

    val xs = (1 to n) map { e => sc.next }
    var ans = java.lang.Long.MAX_VALUE
    for (x <- xs) {
      val c = x.max
      val base = if (c.isDigit) c - '0' + 1 else c - 'A' + 11
      ans = min(ans, java.lang.Long.parseLong(x, base))
    }
    println(ans)
  }
}