here is my prog : please help
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{1249}
const maxn=3001;
var
  a,b           : array[0..maxn] of boolean;
  n,m,i,j,k,l,p : integer;
begin
  readln(m,n);
  fillchar(a,sizeof(a),False);
  fillchar(b,sizeof(b),False);
  for i:=1 to n do
    begin
      l:=0;p:=0;
      for j:=1 to m do
        begin
          read(k);
          if k=1 then
          begin
            b[j]:=True;
            if (l=0) then
            begin
            l:=j;
            end
            else
                begin
                  if (a[l]<>a[j]) then
                    begin
                      writeln('NO');halt;
                    end;
                end;
          end
          else
          begin
            b[j]:=False;
            l:=0;
          end;
          if a[j] then
            begin
              if (p=0) then
              begin
                p:=j;
              end
              else
                begin
                  if (b[p]<>b[j]) then
                    begin
                      writeln('NO');halt;
                    end;
                end;
            end
          else
            p:=0;
        end;
      for j:=1 to m do
        a[j]:=b[j];
    end;
  writeln('YES');
end.
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SABER
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