Prime number formula proof

Question

Can anyone please help with this problem? We have the following formula$$ \pi(n)=n-1+\pi(\lfloor\sqrt{ n }\rfloor)+\sum(-1)^k \lfloor{\frac n {p_{j_1} p_{j_2}...p_{j_k}}\rfloor} $$ where π(n) is the count of prime numbers from 2 to n (including n). The sum is by the subsets ${\{j_1,j_2,...,j_k\}}$ of $\{1,2,...,\pi{(\lfloor\sqrt{n} \rfloor})\} $ and $k$ is from $1$ to $\pi(\lfloor\sqrt{n}\rfloor).$ We have to prove the formula for each natural number $n$.