Hi
If this the date format then the below expression would help you resolve this
Str_date = Datetime.ParseExact(Strinput.ToString.SubString(0,10), “dd.MM.yyyy”, System.Globalization.CultureInfo.InvariantCulture).AddMonths(1).ToString
For more details on data time there is a tutorial in UiPath forum
Have a view on it for details on Datetime
Cheers @Betul_Dundar