Crystal reports brought forward balance issue

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CrystalReports

I am using a formula to get the accumulated balance in a report. That report is running in c# with a date range. I need to to create a line with a brought forward balance to the report to get the actual balance. how to create brought forward balance in crystal report.
The following code is using to get the accumulated balance.

Whileprintingrecords;
Shared Numbervar balance;
Shared Numbervar display;
balance:={@debit}-{@credit};
display:=display+balance;
display