#描述# http://acm.pku.cn/JudgeOnline/problem?id=3300
#格式# ##输入格式##
##输出格式##
#样例1# ##样例输入1##
2 4 40 50 12 14 16 19 0
##样例输出1##
1.19
#限制# 1000ms 32768KB
#提示#
#来源#
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