{"problem":{"name":"素数个数","description":{"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。","description_type":"Markdown"},"platform":"Luogu","limit":{"time_limit":1000,"memory_limit":131072},"difficulty":{"LuoguStyle":"P1"},"is_remote":true,"is_sync":true,"sync_url":null,"sign":"LGB2128"},"statements":[{"statement_type":"Markdown","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。\n\n## Input\n\n输入 $n(2 \\le n \\le 50000)$。\n\n## Output\n\n输出一行，表示 $2\\sim n$ 中的素数个数。\n\n[samples]\n\n## Note\n\n对于所有数据，保证 $2 \\le n \\le 50000$。","is_translate":false,"language":"English"}],"meta":{"iden":"LGB2128","tags":["函数与递归"],"sample_group":[["10\n","4\n"]],"created_at":"2026-03-03 11:09:25"}}