object main{
  object Solver extends InputReader{
    def mapChar(c: Char): Int = {
      if('0' <= c && c <= '9') return c - '0'
      return c - 'A' + 10
    }

    def mapToInt(v: String): Long = {
      val vi = v.map(mapChar)
      val mx = vi.max
      (0L /: vi)(_ * (mx + 1) + _)
    }

    def solve(){
      val n = getInt()
      val a = Array.fill(n)(getStr())
      println(a.map(mapToInt).min)
    }
  }

  // TEMPLATE ------------------------

  def main(args: Array[String]){
    Solver.solve()
  }

  trait InputReader{
    import java.io._
    import java.util._
    protected val stream = System.in
    private val reader = new BufferedReader(new InputStreamReader(stream))
    private var tokenizer = new StringTokenizer(reader.readLine())

    def getStr(): String = {
      while(!tokenizer.hasMoreTokens())
        tokenizer = new StringTokenizer(reader.readLine())
      tokenizer.nextToken()
    }

    def getInt(): Int = getStr().toInt
    def getLong(): Long = getStr().toLong
    def getDouble(): Double = getStr().toDouble
  }
}