Copy Specific chart in excel and paste it in the existing presentation

I have an excel sheet, which includes lots of graphs and charts.
I need to write a macro to copy the specific graphs and paste it inthe existing presentation

For example:

I have workbook called 'graph.xls' and 'MRT.ppt' as presentation
I need to copy the specific charts from 'graph.xls' and paste it in the specific slide of 'MRT.ppt'

I.e : copy 1st &3rd chart & paste it into top of the third slide.

Thanks in advance.