[Ghost]

uses
  crt;

const
  n = 4;

var
  a: array [1..n, 1..n] of integer;
  i, j, s: integer;

begin
  clrscr;
  randomize;
  writeln ('start array:');
  for i := 1 to n do begin
    for j := 1 to n do begin
      a[i, j] := random (50);
      write (a[i, j] : 4);
    end;
    writeln;
  end;
  s := 0;
  for i := 1 to n do inc (s, a[i, i]);
  writeln('summ = ', s);
  readkey;
end.