program Hello;

var
 a: array[1..50] of string;

var
 n, k, i, c: integer;



begin
 readln(n);
 readln(k);
 i := 0;
 c:=0;
 for i := 1 to n do
 begin
 readln(a[i]);

 end;
 for i := 1 to n do
 begin
 if(a[i] = 'A') then k += 1
 else
 if(a[i] = 'C') then k -= 1;

 end;
 if(k <0) then
 begin
 while(k < 1) do
 K += 1;
 c += 1;
 end;
 writeln(c);
end.