Uses Crt;
Var a:array[1..1000] of integer;
i,n,s:integer; TBC:real;
Demc,Deml,max,min:integer;
Begin
Clrscr;
For i:= 1 to 4 do
Begin
Write('Nhap a[',i,']= '); Readln(a[i]);
End;
For i:= 1 to 4 do
Begin
If a[i] mod 2 = 0 then Demc:=Demc+1;
If a[i] mod 2 <> 0 then Deml:=Deml+1;
S:=S+a[i];
TBC:=S/4;
End;
  Writeln;
Write('TBC cua day so nguyen do = ',TBC:1:2);
  Writeln;
  Writeln;
Write(' Cac so chan co trong day la: ');
  For i:= 1 to 4 do If a[i] mod 2 = 0 then write(a[i]:4);
Writeln;
 max:=a[1]; min:=a[1];
  For i:= 2 to 4 do
Begin
If max<a[i] then max:=a[i];
If min>a[i] then min:=a[i];
End;
Write(' Cac so le co trong day la: ');
For i:= 1 to 4 do If a[i] mod 2 = 1 then Write(a[i]:4);
  Writeln;
  Writeln;
Write(' So lon nhat trong day la: ',max);
  Writeln;
Write(' So nho nhat trong day la: ',min);
  Writeln;
  Writeln;
Writeln(' Co ',Demc,' so chan trong day so tren');
Writeln(' Co ',Deml,' so le trong day so tren');
Readln
End.
*Nhớ tick và chọn làm câu trả lời hay nhất giúp mình với nhé! Thanks :D

program Bai_1;

uses crt;

var n,i : integer; s:real;

begin

clrscr;

write ('Nhap n :'); readln(n);

for i:= 1 to n do s:=s+1/(2*i);

write ('S=',s);

readln;

end