program oken; uses crt; var s: string; i,dem: byte; begin clrscr; write('nhap 1 xau bat ky: '); readln(s); for i:=1 to length(s) do if s[i]='a' then dem:=dem+1; writeln('so ki tu a co trong xau: ',dem); readln; end.
uses crt; var s:string; i,dem:byte; begin clrscr; write('Nhap xau: '); readln(s); for i:=1 to length(s) do if s[i]='a' then dem:=dem+1; writeln('So ki tu a co trong xau la: ',dem); readln end.
