HI , and a good week , programmers !

I need a UDF to count until it find
the same value in a range of cells :

eg: in A1 is value TRUE , in A2 the same value ,
in A3 the same value ( TRUE ) , in A4 the same value ,
but in cell A5 the value is FALSE ; in cell A6 the value is
again TRUE , etc .
the good result of this UDF is 4 , because I need this
UDF to count only untill it find the same value ;

Please very much to help me , and thousand
of thanks in advance