Program Sherilusha;

uses crt;
const n = 20;
var
  a:array [1..n] of integer;
  sdvig,i,k:integer;
begin
  randomize;
  for i:=1 to n do
    begin
      a[i]:=random(100)-50;
      write(a[i]:3,' ');
    end;
  writeln();
  sdvig:=0;
  for i:=1 to n do
    if a[i]=0 then
        sdvig:=sdvig+1
    else
      begin
        a[i-sdvig]:=a[i];
      end;
  k:=n-sdvig;
  for i:=1 to k do
    write(a[i]:3,' ');
end.

Verified answer

uses crt;
var
  m,i,k:integer; a:array [1..100] of integer;
begin
  clrscr; randomize;
  write('Количество элементов массива: ');readln(k);
  for i:=1 to k do
  begin
    a[i]:=random(100)-50;
    write(a[i],' ');
  end;
  m:=0;
  writeln;
  for i:=1 to k do
    if a[i]=0 then inc(m)
    else a[i-m]:=a[i];k:=k-m;
  for i:=1 to k do
    write(a[i],' ');readln;
end.