using System;

​

public struct CHITIET

{

    public string TenMatHang;

    public int SoLuong;

    public double DonGia;

}

​

public struct DONHANG

{

    public string TenCuaHang;

    public string TenKhachHang;

    public CHITIET[] DanhSach;

}

​

public class Program

{

    public static int NhapSoNguyen(string note) {

        Console.WriteLine(note);

        int n = int.Parse(Console.ReadLine());

        return n;

    }

    public static CHITIET NhapChiTietDonHang(string note) {

        Console.WriteLine(note);

        CHITIET n;

        Console.Write("Nhap ten mat hang: ");

        n.TenMatHang = Console.ReadLine();

        Console.Write("Nhap so luong: ");

        n.SoLuong = int.Parse(Console.ReadLine());

        Console.Write("Nhap don gia: ");

        n.DonGia = double.Parse(Console.ReadLine());

        return n;

    }

    public static DONHANG NhapDonHang(string note) {

        Console.WriteLine(note);

        DONHANG n;

        Console.Write("Nhap ten cua hang: ");

        n.TenCuaHang = Console.ReadLine();

        Console.Write("Nhap ten khach hang: ");

        n.TenKhachHang = Console.ReadLine();

        Console.WriteLine("Nhap danh sach chi tiet don hang: ");

        int m = NhapSoNguyen("Nhap so luong trong danh sach:");

        n.DanhSach = new CHITIET [m];

        for (int i = 0; i < m; i++) {

            n.DanhSach[i] = NhapChiTietDonHang("Nhap chi tiet tung don hang: ");

        }

        return n;

    }

    public static void XuatChiTietDonHang(CHITIET n) {

        Console.WriteLine("Ten mat hang la {0}", n.TenMatHang);

        Console.WriteLine("So luong cua mat hang {0} la {1}", n.TenMatHang, n.SoLuong);

        Console.WriteLine("Don gia cua mat hang {0} la {1}", n.TenMatHang, n.DonGia);

    }

    public static CHITIET TimChiTietDonHangLonNhat(DONHANG d) {

        double max = d.DanhSach[0].SoLuong * d.DanhSach[0].DonGia;

        int chitiet = 0;

        for (int i = 0; i < d.DanhSach.Length; i++) {

            if (d.DanhSach[i].SoLuong * d.DanhSach[i].DonGia > max) {

                max = d.DanhSach[i].SoLuong * d.DanhSach[i].DonGia;

                chitiet = i;

            }

        }

        return d.DanhSach[chitiet];

    }

    public static void GiaiPhuongTrinhBacNhat(int a, int b) {

        if (a == 0 && b == 0) {

            Console.Write("Phuong trinh vo so nghiem");

        } else if (a == 0 && b != 0) {

            Console.Write("Phuong trinh vo nghiem");

        } else if (a != b) {

            Console.Write("Phuong trinh co mot nghiem la {0}", -b/a);

        }

    }

    public static int[] NhapMang(string note) {

        Console.WriteLine(note);

        int[] arr;

        int n = NhapSoNguyen("Nhap do dai mang:");

        arr = new int[n];

        for (int i = 0; i < n; i++) {

            arr[i] = NhapSoNguyen("Nhap tung phan tu trong mang:");

        }

        return arr;

    }

    public static bool KiemTraSoDoiXung(int n) {

        int x = n, temp = 0, y = 0;

        if (n < 11) {

            return false;

        }

        while (x != 0) {

            temp = x % 10;

            y = y * 10 + temp;

            x /= 10;

        }

        if (y == n) {

            return true;

        }

        return false;

    }

    public static int TimSoDoiXungNhoNhatTrongMangSoNguyen(int[] arr) {

        int min = 0;

        for (int i = 0; i < arr.Length; i++) {

            if (KiemTraSoDoiXung(arr[i])) {

                min = arr[i];

                break;

            }

        }

        for (int i = 0; i < arr.Length; i++) {

            if (KiemTraSoDoiXung(arr[i]) && arr[i] < min) {

                min = arr[i];

            }

        }

        return min;

    }

    public static void Main()

    {

        int[] arr;

        arr = NhapMang("Nhap mang:");

        int result = TimSoDoiXungNhoNhatTrongMangSoNguyen(arr);

        Console.WriteLine("So doi xung nho nhat trong mang so nguyen la {0}",result);

        DONHANG d;

        d = NhapDonHang("Nhap don hang:");

        XuatChiTietDonHang(TimChiTietDonHangLonNhat(d));

    }

}