var
    a: array [1..100] of integer;
    i, p, n: integer;

begin
    p := 1;
    read(n);
    
    for i := 1 to n do
    begin
        read(a[i]);
        if a[i] mod 2 = 0 then
            p := p * a[i];
    end;
    
    writeln(p);
end.

Verified answer

program csdnciuo;

uses crt;

'var a:array [1..100] of integer;

       i,p,n:integer;

begin

clrscr;

readln(n);

for i:=1 to n do

readln(a[i]);

p:=1;

for i:=1 to n do

if a[i] mod 2 =0 then p:=p*a[i];

writeln(p);

readln;

end.