Banka.cs

using System;
using System.Collections.Generic;

internal class Program {

    static void Main(string[] args) {
        UrocenyUcet ucet = new UrocenyUcet("prvni", 20);
        ucet.Stav();
        ucet.VlozHotovost(22);
        ucet.Stav();
        ucet.VyberHotovosti(30);
        ucet.Stav();
        ucet.VyberHotovosti(30);
        ucet.Stav();
    }
}

class BankovniUcet {
    private string CisloUctu;
    private double StavUctu;

    public BankovniUcet(string ucet, double stav) {
        CisloUctu = ucet;
        StavUctu = stav;
    }

    public virtual void VlozHotovost(double castka) {
        StavUctu += castka;
    }

    public void VyberHotovosti(double castka) {
        if (castka > StavUctu) {
            throw new Exception();
        }
        StavUctu -= castka;
    }

    public double Zustatek() {
        return StavUctu;
    }

    public void PrevoPenez(double castka, BankovniUcet ucet) {
        if (castka > StavUctu) {
            throw new Exception();
        }
        StavUctu -= castka;
        ucet.VlozHotovost(castka);
    }

    public void Stav() {
        Console.WriteLine($"Na účtu {CisloUctu} je {StavUctu} Kč");
    }
}

class UrocenyUcet: BankovniUcet {
    public UrocenyUcet(string ucet, double stav): base(ucet, stav) {
    }

    public override void VlozHotovost(double castka) {
        base.VlozHotovost(castka * 1.03) ;
    }
}