C1:
Uses crt;

Var a: array[1..500] of integer;

i,n,dem: integer;

Begin

Clrscr;

Write(' Nhap so ptu N= ');  Readln (n);

dem:=0;
For i:=1 to n do

Begin

Write(' Nhap a[',i,'] = ');  Readln (a[i]);

If a[i] mod 2=0 then dem:=dem+1;

End;

Writeln ('So cac so chan trong mang la: ',dem);

Readln;

End.
C2:

Uses crt;

Var a: array[1..500] of integer;

i,n,dem: integer;

Begin

Clrscr;

Write(' Nhap so ptu N= ');  Readln (n);

dem:=0;
For i:=1 to n do

Begin

Write(' Nhap a[',i,'] = ');  Readln (a[i]);
End;

For i:= 1 to n do
If a[i] mod 2<>0 then dem:=dem+1;

Writeln ('So cac so chan trong mang la: ',dem);

Readln;

End.
C3: 

Uses crt;
Var a: array[1..500] of integer;
i,n,tsd: integer;
Begin
Clrscr;
Write(' Nhap so ptu N= '); Readln(n);
tsd:=0;
For i:=1 to n do
Begin
Repeat
Write(' Nhap a[',i,'] = '); Readln(a[i]);
Until a[i]>0;
End;
For i:= 1 to n do tsd:=tsd+a[i];
Writeln ('So cac so chan trong mang la: ',tsd);
Readln;
End.

câu 1:

uses crt;

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

i,n,d: integer;

begin

clrscr;

write ('nhap n: ');  readln (n);

for i:=1 to n do

begin

write ('nhap phan tu thu ',i,': ');  readln (a[i]);

if a[i] mod 2=0 then d:=d+1;

end;

writeln ('trong mang co ',d,' so chan');

readln;

end.

câu 2:

uses crt;

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

i,n: integer;

begin

clrscr;

write ('nhap n: ');  readln (n);

for i:=1 to n do

begin

write ('nhap phan tu thu ',i,': ');  readln (a[i]);

end;

write ('cac so le trong mang: ');

for i:=1 to n do if a[i] mod 2<>0 then write (a[i],' ');

readln;

end.

câu 3:

uses crt;

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

i,n,s: integer;

begin

clrscr;

write ('nhap n: ');  readln (n);

for i:=1 to n do

begin

write ('nhap phan tu thu ',i,': ');  readln (a[i]);

if a[i]>0 then s:=s+a[i];

end;

writeln ('tong cac phan tu duong: ',s);

readln;

end.