uses crt;
var a:array[1..100]of integer;
i,n,t:integer;
begin
clrscr;
write('Nhap n='); readln(n);
for i:=1 to n do
begin
write('A[',i,']='); readln(a[i]);
end;
t:=0;
for i:=1 to n do
if (a[i] mod 3=0) and (i mod 2=0) then t:=t+a[i];
writeln('Tong cac so chia het cho 3 o vi tri chan la: ',t);
readln;
end.