Проверка рядка на наличии его во множестве.

program pr1;
uses crt;
var s1,r_st,sl: string;
p,i,k: byte;
flag: boolean;
begin;
clrscr;
writeln('Input string->');
readln(s1);
r_st:=s1;
flag:=true;
while flag do
begin
    flag:=false;
    for i:=1 to length(r_st)do
    if r_st[i] in ['0' .. '1']
    then
    writeln(r_st,' 2-chnoe chuslo');
    if r_st[i] in['0' .. '8']
    then
    writeln(r_st,' Vosmerichnoe chuslo');
    if r_st[i] in['0' .. '9']
    then
    writeln(r_st,' Desyatkovoe chuslo')
    else
    writeln(r_st, 'ne chuslo');
 
end; 
readln;
end.

program pr1;
uses crt;
var s: string;
    i,k2,k8,k10: byte;
begin;
clrscr;
writeln('Input string->');
readln(s);
k2:=0;k8:=0;k10:=0;
for i:=1 to length(s)do
if s[i] in ['0' .. '1'] then
 begin
  k2:=k2+1;
  k8:=k8+1;
  k10:=k10+1;
 end
else if s[i] in ['2' .. '7'] then
 begin
  k8:=k8+1;
  k10:=k10+1;
 end
else if s[i] in ['8','9'] then k10:=k10+1;
if k2=length(s) then writeln('Dvoichnoe chislo')
else if k8=length(s)then writeln(' Vosmerichnoe chuslo')
else if k10=length(s) then  writeln(' Desyatkovoe chuslo')
else writeln('ne chuslo');
readln
end.

program pr1;
uses crt;
var s1,r_st: string;
k2, k8, k10, i: byte;
begin;
clrscr;
writeln('Vvedite chuslo->');
readln(s1);
writeln('Chislo ',s1,' mozhe bytu:');
r_st:=s1;
for i:=1 to length(r_st)do
    if r_st[i] in ['0' .. '1']
    then
    begin
    inc(k2); inc(k8); inc(k10)
    end
    else
    if r_st[i] in['2' .. '7']
    then
    begin
    inc(k8); inc(k10)
    end
    else
    if r_st[i] in['8' .. '9']
    then
    inc(k10)
    else
    writeln(r_st, ' ne chuslo');
if k2=length(r_st) then writeln('Dvoichnoe chislo');
if k8=length(r_st)then writeln(' Vosmerichnoe chuslo');
if k10=length(r_st) then  writeln(' Desyatkovoe chuslo');
readln;
end.