{"raw_statement":[{"iden":"statement","content":"编程求 $2\\sim n$（$n$ 为大于等于 $2$ 的正整数）中有多少个素数。"},{"iden":"input","content":"输入 $n(2 \\le n \\le 50000)$。"},{"iden":"output","content":"输出一行，表示 $2\\sim n$ 中的素数个数。"},{"iden":"note","content":"对于所有数据，保证 $2 \\le n \\le 50000$。"}],"translated_statement":null,"sample_group":[["10\n","4\n"]],"show_order":[],"formal_statement":null,"simple_statement":null,"has_page_source":false}