using System;
public class Program
{
public static void Main()
Console.WriteLine("How many people will be in the party?");
int Pnum = int.Parse(Console.ReadLine());
int Pnum1 = Pnum/13;
int Pnum2 = Pnum1+1;
if (Pnum%13 == 0)
Console.WriteLine("you'll need " + Pnum1 + " pizza trays");
else
Console.WriteLine("you'll need " + Pnum2 + " pizza trays");
}