Program letcnt;
uses crt;

var
ret:string;
len,cis,acka:byte;

begin
clrscr;
write('Zadaj retazec znakov: ');
readln(ret);

len := length(ret);
cis := 1;
while(cis <= len) do
begin
if(copy(ret, cis, 1) = 'a') then
acka := acka + 1;
cis := cis + 1;
end;

writeln('Pocet pismen a v retazci: ',acka);
readln;
end.