score_list = [65,92,78,90,45,83,57,96]
score_dict = {'high':[],'middle':[],'low':[]}
for score in score_list:
    if score >= 90:
       score_dict['high'].append(score)
    elif score >= 60:
       score_dict['middle'].append(score)
    else:
       score_dict['low'].append(score)
print(score_dict)