private void placeIdentityDiscs() {
		while (getElementCoverage(IdentityDisc.class) < COVERAGE) {
			final Position randomPos = getRandomPosition();
			final IdentityDisc idDisc = new IdentityDisc(grid);
			if (grid.validPosition(randomPos) && canHaveAsElement(randomPos, idDisc))
				grid.addElementToPosition(idDisc, randomPos);
		}
	}