uses crt;
var n:string; i,dem:longint;
begin
clrscr;
   write('N=');readln(n);
   for i:=1 to length(n) do
   if (n[i]='0')or(n[i]='2')or(n[i]='4')or(n[i]='6')or(n[i]='8')then dem:=dem+1;
   writeln('So chu so chan cua ',n,': ',dem);
readln
end.

//////////////////////////////

Test:

 uses crt;
var  a : array[1..100] of integer;
i,d : integer; n : int64;
st : string;
begin clrscr;
d:=0;
write('Nhap so n :'); readln(n);
str(n,st);
for i:=1 to length(st) do val(st[i],a[i]);
for i:=1 to length(st) do if a[i] mod 2 = 0 then d:=d+1;
write('So luong so chan la :',d);
readln
end.