import scala.annotation.tailrec

object Problem280 {

  def proc(z: List[BigDecimal]) = {

    @tailrec
    def calcLastTheta(child: BigDecimal, parent: BigDecimal, z: List[BigDecimal]): (BigDecimal, BigDecimal) = {
      z match {
        case (head :: Nil) => (child, parent)
        case (head :: next :: tail) => {
          val c = child * head
          val p = parent * next

          // 毎回約分することで桁あふれを起こさない
          val g = gcd(c, p)
          val rc = c / g
          val rp = p / g
          calcLastTheta(rc, rp, z.tail)
        }
        case _ => throw new IllegalStateException("2 <= N <= 50なので起こり得ない")
      }
    }

    // θjを求める
    val (child, parent) = calcLastTheta(1, 1, z)

    // gcdで最大公約数求めて約分する
    val g = gcd(child, parent)
    val reductionChild = child / g
    val reductionParent = parent / g

    // 1/(child/parent) なので parent/child を表示
    reductionParent + "/" + reductionChild
  }

  @tailrec
  def gcd(m: BigDecimal, n: BigDecimal): BigDecimal = {
    if (n == 0) {
      m
    } else {
      gcd(n, m % n)
    }
  }

  //  N
  //  z1 z2 ... zN
  def main(args: Array[String]) {
    val N = scala.io.StdIn.readInt()
    val z = scala.io.StdIn.readLine().split(" ").map(x => BigDecimal(x)).toList

    val result = proc(z)
    println(result)
    // test
  }

  def test = {
    assert(proc(List(20, 40)) == "2/1")
    assert(proc(List(10, 10, 10)) == "1/1")
    assert(proc(List(20, 60)) == "3/1")
  }
}