uses crt;

var S : string; i, d, k : integer;

begin

clrscr;

write('Nhap xau ki tu : '); readln(S);

write('Cac ki tu xuat hien 1 lan : ');

for i := 1 to length(S) do

    begin

        d := 0;

        for k := 1 to length(S) do

            if (i <> k) and (S[i] = S[k]) then

                d := 1;

        if d = 0 then write(S[i],' ');

    end;

readln

end.

uses crt;var s:string[30];    ch,x:char;    i:byte;    dem:array['A'..'Z']of byte;BEGIN     clrscr;     

write('Nhap vao xau s=');     readln(s);     for ch:='A' to 'Z' do dem[ch]:=0;     for i:=1 to length(s) do         begin         x:=upcase(s[i]);         if (x>='A') and (x<='Z')            then            dem[x]:=dem[x]+1;         end;     for ch:='A' to 'Z' do         if dem[ch]<>0 then                 

writeln('So luong ki tu',ch,'la',dem[ch]);     readln;END.