using System;

using System.Globalization;     

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        // 補助金額

        var subsidy = 20000m;

        // 到職日

        var onBoardDay = new DateTime(2020,4,20);

        // 計算基準日

        var basicDay = new DateTime(2020,6,1);

        var yearTotalDays = (basicDay - basicDay.AddYears(-1)).Days;

        var onBoardCountDay =  (basicDay - onBoardDay).Days ;

​

        var ratio = onBoardCountDay < 0 ? 0m : ((decimal)onBoardCountDay / (decimal)yearTotalDays);

        var result = ratio > 1 ? 1 * subsidy : ratio * subsidy;

        Console.WriteLine("到職日期:{0:yyyy/MM/dd}",onBoardDay);

        Console.WriteLine("到職天數:{0}, 補助比例:{1:p2}, 旅遊補助:{2:n0}", onBoardCountDay, ratio, result);

    }

}