public static void Main()
var toanhoc = new ToanHoc();
Console.WriteLine(toanhoc.DaoChuoi(Console.ReadLine()));
for (int i =0; i<= n ; i++)
public int TinhGiaiThua(int n1)
for (int j =1; j<=n1; j++)
public string DaoChuoi(string chuoibandau)
var dem = chuoibandau.Length;
var chuoiketqua = new char[dem];
for (int i =0; i<= dem -1 ; i++)
chuoiketqua[dem-i-1] = chuoibandau[i];
return new string(chuoiketqua);