Dim FirstDate As Date    ' Declare variables.
Dim IntervalType As String
Dim Number As Double 'В оригинале 'Integer'
Dim Msg
IntervalType = "yyyy"    ' "m" specifies months as interval.
FirstDate = InputBox("Enter a date")
Number = InputBox("Enter number of year to add")
Msg = "New date: " & DateAdd(IntervalType, Number, FirstDate)
MsgBox Msg

Public Function dhIsLeapYear(Optional varDate As Variant) As Boolean
    ' Is the supplied year a leap year?
    ' Check the day number of the day
    ' after Feb 28 to find out.
    
    ' From "Visual Basic Language Developer's Handbook"
    ' by Ken Getz and Mike Gilbert
    ' Copyright 2000; Sybex, Inc. All rights reserved.
    
    ' In:
    '   varDate (Optional):
    '       If unspecified, use the current year.
    '       If a date, use the year of the specified date.
    '       If a valid integer (between 100 and 9999),
    '           use that value as the year, otherwise use the current year.
    '       If any other data type, act as if varDate wasn't specified
    '        (that is, use the current year).
    ' Out:
    '   Return value:
    '       Boolean indicating whether the specified year
    '       is a leap year.
    ' Example:
    '   If dhIsLeapYear() Then
    '     ' You know the current year is a leap year.
    '
    '   If dhIsLeapYear(1956) Then
    '     ' You know 1956 was a leap year.
    '
    '   If dhIsLeapYear(#12/1/92#) Then
    '     ' You know 1992 was a leap year.
    
    ' Missing? Use the current year.
    If IsMissing(varDate) Then
        varDate = Year(Date)
    
    ' Is it a date? Then use that year.
    ElseIf VarType(varDate) = vbDate Then
        varDate = Year(varDate)
        
    ' Is it an integer? Use that value, if it's value.
    ' Otherwise, use the current year.
    ElseIf VarType(varDate) = vbInteger Then
        ' Only years 100 through 9999 are allowed.
        If varDate <  100  Or varDate >  9999  Then
            varDate = Year(Date)
        End If
        
    ' If it's not a date or an integer, just use the
    ' current year.
    Else
        varDate = Year(Date)
    End If
    dhIsLeapYear = (Day(DateSerial(varDate,  2 ,  28 ) +  1 ) =  29 )
End Function