P3912 Number of Primes

Find the number of primes among $1, 2, \cdots, N$.

One line containing an integer $N$.

One line containing an integer, representing the number of primes.

For $40\%$ of the testdata, $1 \le N \le 10^6$. For $80\%$ of the testdata, $1 \le N \le 10^7$. For $100\%$ of the testdata, $1 \le N \le 10^8$. Translated by ChatGPT 5