How to get highest open interest symbol name in watchlist

AFL Programming
1

Hi all
I should appreciate it if you would let me know how to find highest open interest symbol name in watchlist.
. Please consider the following system as an example:

//*******************************************************
listname = CategoryFind("OI", categoryWatchlist );

//******************************************************
symnu =0;
maxoisymno = 1000;
symbolno = 0;
tets="";
syno = 0;
entrydate = 0; 
entrytime = 0; 
dat = DateNum() ; 
TM  = TimeNum(); 
if ( Status( "stocknum" ) == 0 )    
{ 
	//StaticVarRemove("*");
	for( k = 1; k < BarCount; k++ )
	{		
		List = CategoryGetSymbols(categoryWatchlist, listname );
		MaxOI = 0; 
		for(n = 0; (Symbol = StrExtract(List, n))  != "";  n++) 
		{
			symbolno[k] = n;
			f = Foreign( Symbol, "I");
			MaxOI = IIf(n == 0, f, Max(f, MaxOI));
			if(MaxOI[k] == f[k])
			{
				maxoisymno = n;
				StaticVarSet( "~maxopnum", maxoisymno);
			}
			RestorePriceArrays(); 
			symnu[k] = maxoisymno;
			
		}
	}
}

syno = StaticVarGet ( "~maxopnum" );


Filter = 1;
AddColumn( DateTime(), "Date", formatDateTime , colorDefault, bkgndColor = colorDefault, width = 150, barchart = Null);

AddColumn(Foreign(StrExtract( List, 0 ), "I"),"440CE",1.2, colorDefault, bkgndColor = colorDefault, width = 75, barchart = Null);
AddColumn(Foreign(StrExtract( List, 1 ), "I"),"450CE",1.2, colorDefault, bkgndColor = colorDefault, width = 75, barchart = Null);
AddColumn(Foreign(StrExtract( List, 2 ), "I"),"460CE",1.2, colorDefault, bkgndColor = colorDefault, width = 75, barchart = Null);
AddColumn(Foreign(StrExtract( List, 3 ), "I"),"470CE",1.2, colorDefault, bkgndColor = colorDefault, width = 75, barchart = Null);

AddColumn(MaxOI,"HighestOI",1.2, colorDefault, bkgndColor = colorDefault, width = 75, barchart = Null);
AddColumn(symnu,"HighestOINum",1.2, colorDefault, bkgndColor = colorDefault, width = 100, barchart = Null);
AddTextColumn(StrExtract( List, syno ),"HighestOISymbol",1.2, colorDefault, bkgndColor = colorDefault, width = 100);

Thanks.