import java.util.Scanner

object Problem164 {

  def charToLongValue(c: Char): Long = {
    c match {
      case x if x < 58 => x.asDigit // [0-9] -> 0..9
      case x => x - 65 + 10 // [a-z] -> 10..35
    }
  }

  def calcDecimalValue(s: String): Long = {
    val longs = s.map(charToLongValue)
    val decimal = longs.max + 1 // 0-indexの最大数値を進数に変換
    longs.foldLeft(0L)((a, b) => a * decimal + b)
  }

  def proc(numbers: Seq[String]): Long = {
    numbers.map(calcDecimalValue).min
  }

  def main(args: Array[String]): Unit = {
    val sc = new Scanner(System.in)
    val n = sc.next.toInt
    val v = Seq.fill(n)(sc.next)

    val result = proc(v)
    println(result)
  }
}