Làm lịch

program inlich;
uses crt;
var i,j,nam,thang,k,l:longint;
    s:string;

procedure nhap;
 begin
  clrscr;
  write('nhap vao nam: ');readln(nam);
  write('nhap vao thang: ');readln(thang);
 end;

function ktn(i:integer):boolean;
 begin
  if ((i mod 100<>0)and(i mod 4=0))or(i mod 400=0) then ktn:=true
  else ktn:=false;
 end;

procedure tinh;
 begin
  k:=0;
  for i:=1 to nam-1 do
  begin
    if ktn(i) then k:=k+366
    else k:=k+365;
  end;
  for i:=1 to thang-1 do
  begin
    if i in[1,3,5,7,8,10,12] then k:=k+31;
    if i in[4,6,9,11] then k:=k+30;
    if (i=2) and(ktn(nam)) then k:=k+29;
    if (i=2)and (not ktn(nam)) then k:=k+28;
  end;
  k:=(k+1) mod 7;
 end;

procedure xuat;
 begin
  clrscr;
  writeln('  LICH THANG ',thang,' NAM ',nam);
  writeln('  CN HAI  BA  TU NAM SAU BAY');
  if thang in[1,3,5,7,8,10,12] then l:=31;
  if thang in[4,6,9,11] then l:=30;
  if (thang=2) and (ktn(nam)) then l:=29;
  if (thang=2)and(not ktn(nam)) then l:=28;

  for i:=1 to k-1 do write('    ');
  for i:=1 to l do
  begin
    str(i,s); while length(s)<4 do s:=' '+s;
    write(s);
    k:=(k+1)mod 7;
    if k=0 then writeln;
  end;

  readln;
 end;

begin
 nhap;
 tinh;
 xuat;
end.