24.赋值问题
http://acm.fzu.edu.cn/problem.php?pid=1055
import sys
line_left=0
for read_in in sys.stdin.readlines():
if not read_in:
break
if line_left==0:
line_left=int(read_in.rstrip())
if line_left==-1:
break
certain=['a'] # 用于保存具有确定值的变量
else:
first,second=tuple([x for x in read_in.rstrip().split('=')])
if second in certain:
certain.append(first)
line_left-=1
if line_left==0:
certain.sort()
print(' '.join([each for each in certain]))