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using System;

namespace ConsoleApp1
{
    class Program
    {
        public static int F (int c)
        {
            int d = 1;
            for (int i = 1; i <= c; i++)
            {
                d *= i;
            }
            return d;
        }
        static void Main(string[] args)
        {
            double s = 0;
            for (int i = 1; i < 7; i++) {
                s += Math.Pow(-1, i) * Math.Pow(5, i) / F(i);
            }
            Console.WriteLine(s);
        }
    }
}

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