Bài 1:

uses crt;
var f1,f2:text;
i,n,t:longint;
a:array[1..1000] of longint;
begin
    assign(f1,'SONGUYEN.INP');reset(f1);
    assign(f2,'TONGCHAN.OUT');rewrite(f2);
    readln(f1,n);
    for i:=1 to n do
       read(f1,a[i]);
    for i:=1 to n do
       if a[i] mod 2 = 1 then t:=t+a[i];
    writeln(f2,t);

    close(f1);close(f2);
end.

Bài 2:

uses crt;
var
i,n,t:longint;
a:array[1..1000] of longint;
begin
    clrscr;
    readln(n);
    for i:=1 to n do
       read(a[i]);
    readln;
    for i:=1 to n do
       if a[i] mod 5 = 0 then t:=t+a[i];
    writeln(t);
readln;
end.

1.

program phuongt;
uses crt;
  var A: array[1..500] of integer;
        ip, op: text;
        i, n, s: integer;
begin
        clrscr;
        assign(ip, 'E:\SONGUYEN.txt');
        assign(op, 'E:\TONGCHAN.txt');
        reset(ip);
        rewrite(op);
        readln(ip, n);
        writeln(op, 'n = ', n);
        for i:=1 to n do readln(ip,A[i]);
        for i:=1 to n do if A[i] mod 2 <> 0 then s:=s+A[i];
        write(op, 'Tong cac so le trong day: ', s);
        close(ip);
        close(op);
        write('Mo file de xem ket qua');
        readln
end.

2.

program phuongt;
uses crt; 
  var A: array[1..50] of integer;
        n, i: integer;
begin
        clrscr;
        write('Nhap n (n<=50) = '); readln(n);
        if n>50 then write('Ngoai vung du lieu!.') else
        begin
                for i:=1 to n do
                begin
                         write('A[', i, '] = '); readln(A[i]);
                end;
                for i:=1 to n do if A[i] mod 5 = 0 then write(A[i]:3);
        end;
        readln
end.