{"raw_statement":[{"iden":"statement","content":"栅栏由 $N$ 块木板组成。\n\n因为是栅栏，所以第 $i$ 块的右边界与第 $i+1$ 块的左边界的高度一样。\n\n告诉你这些木板的边界的高度与这些木板的宽度，输出这些木板的总面积。"},{"iden":"input","content":"第一行一个整数 $N$。\n\n第二行 $N+1$ 个整数，表示每个边界的高度。\n\n第三行 $N$ 个整数，表示每块木板的宽度。"},{"iden":"output","content":"一行一个保留一位小数的实数，总面积。"},{"iden":"note","content":"样例解释：\n\n![](https://cdn.luogu.com.cn/upload/image_hosting/doy8i2lm.png)![](https://cdn.luogu.com.cn/upload/image_hosting/3q9oe7v5.png)\n\n$N\\leq 10000$，高度和宽度 $\\leq 100$。\n\n译自 [CCC2021 S2](https://cemc.math.uwaterloo.ca/contests/computing/past_ccc_contests/2021/ccc/seniorEF.pdf)。"}],"translated_statement":null,"sample_group":[["3\n2 3 6 2\n4 1 1\n","18.5"],["4\n6 4 9 7 3\n5 2 4 1\n","75.0"]],"show_order":[],"formal_statement":null,"simple_statement":null,"has_page_source":false}