- Time limit: 1.00 s
- Memory limit: 512 MB
Your task is to calculate how many of the first $n$ positive integers are divisible by at least one of the given prime numbers.
Input
The first input line has two integers $n$ and $k$.
The second line has $k$ prime numbers $a_1,a_2,\ldots,a_k$.
Output
Print one integer: the number integers within the interval $1,2,\ldots,n$ that are divisible by at least one of the prime numbers.
Constraints
- $1 \le n \le 10^{18}$
- $1 \le k \le 20$
- $2 \le a_i \le n$
Input:
20 2
2 5
Output:
12
Explanation: the $12$ numbers are $2,4,5,6,8,10,12,14,15,16,18,20$.