{"trustable":true,"sections":[{"title":"Description","value":{"format":"MD","content":"求 $1,2,\\cdots,N$ 中素数的个数。\n"}},{"title":"Input","value":{"format":"MD","content":"一行一个整数 $N$。\n"}},{"title":"Output","value":{"format":"MD","content":"一行一个整数,表示素数的个数。\n"}},{"title":"Sample 1","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e10\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e4\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}},{"title":"Hint","value":{"format":"MD","content":"对于 $40\\%$ 的数据,$1 \\le N \\le 10^6$。\n\n对于 $80\\%$ 的数据,$1 \\le N \\le 10^7$。\n\n对于 $100\\%$ 的数据,$1 \\le N \\le 10^8$。\n"}}]}