Pascal/Turbo Pascal - programa promedio de nota

uses crt;

var

	beca,suma,grado,lapso,num,i,j:word;

	nomApell:string;

	materia:array[1..100] of byte;

	prom:real;

begin

	clrscr;

	suma:=0;

	prom:=0;

	write('Nro de Alumnos:');

	readln(num);

	writeln;

	for i:=1 to num do begin

		writeln('Alumno Nro ',i);

		writeln;

		write('Apellido y Nombre: ');

		readln(nomApell);

		writeln;

		write('Grado: ');

		readln(grado);

		writeln;

		write('Lapso: ');

		readln(lapso);

		writeln;

		writeln('Notas');

		writeln;

		case grado of

			1,2,3:

			begin

				for j:=1 to 5 do begin

					write('Materia ',j,': ');

					readln(materia[i]);

					suma:=suma+materia[i];

				end;

				prom:=suma/j;

				writeln('Promedio: ',prom:4:2);

			end;

		end;

		if (prom >= 18) and (prom <= 20) then begin

			beca:=55000;

			writeln; writeln;

			writeln('Monto de la Beca: ',beca);

		end

		else if (prom >= 16) and (prom < 18) then begin

			beca:=35000;

			writeln; writeln;

			writeln('Monto de la Beca: ',beca);

		end;

	end;

end.