using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace No280
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			var n = Convert.ToInt32(Console.ReadLine ());
			string[] line = Console.ReadLine ().Split(' ');
			long[] wheels = line.Select (s => Convert.ToInt64 (s)).ToArray();

			Console.WriteLine (wheels[n-1].ToString () + "/" + wheels[0].ToString());
		}
	}
}