program z716;
uses crt;
const n=10;
var a:string[n];
s,i:integer;
f:string[n];
Begin
clrscr;
writeln('vvesti');
readln(a);
f:='b';
s:=0;
for i:=1 to lenght(a) do begin
if (f=copy (a,i,1) then begin
s:=s+1;
end;end;
if s:=0 then write('net') else
writeln('s=' ,s:4);
readln;
END.