uses crt;
var a:string;
n,i,kt,kt1,t,x,kt2,j,d:integer;
b:array[1..255]of integer;
begin
clrscr;
write('Nhap so chu so:'); readln(n);
repeat
write('Nhap so a='); readln(a);
kt:=0;
for i:=1 to length(a) do
if not(a[i] in ['0'..'9']) then kt:=1;
if kt=0 then
begin
kt1:=0;
if length(a)<>n then kt1:=1;
end;
until (kt=0) and (kt1=0);
writeln('So chu so cua so ',a,' la: ',n);
d:=length(a);
t:=0;
for i:=1 to d do
begin
val(a[i],b[i],x);
t:=t+b[i];
end;
writeln('Tong cac chu so sau khi chia cho 3 la: ',t/3:4:2);
writeln('Cac chu so cua so ',a,' la so nguyen to la: ');
for i:=1 to d do
if b[i]>1 then
begin
kt2:=0;
for j:=2 to b[i]-1 do
if b[i] mod j=0 then kt2:=1;
if kt2=0 then write(b[i]:4);
end;
readln;
end.