//PascalABC.NET 3.1 сборка 1239
uses System;
uses System.Collections;

begin
    var d := DateTime.Today;
    repeat
        d := d.AddDays(1);
    until d.DayOfWeek = DayOfWeek.Sunday;
    
    var Sundays := new Dictionarylt;integer, integergt;();
    
    repeat
        if Sundays.ContainsKey(d.Year) then
            Sundays[d.Year] += 1
        else
            Sundays.Add(d.Year, 1);
        
        d := d.AddDays((-7));
    until d.Year lt;= 1;
    
    var max := Sundays.Values.Max;
    Sundays.Where(x -gt; x.Value = max).Println;
end.